weblayer/browser/persistence/browser_persister.cc - chromium/src - Git at Google

 // Copyright 2020 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "weblayer/browser/persistence/browser_persister.h"

 #include <stddef.h>

 #include <algorithm>
 #include <utility>
 #include <vector>

 #include "base/bind.h"
 #include "components/sessions/content/content_serialized_navigation_builder.h"
 #include "components/sessions/content/session_tab_helper.h"
 #include "components/sessions/core/command_storage_manager.h"
 #include "components/sessions/core/session_command.h"
 #include "components/sessions/core/session_constants.h"
 #include "components/sessions/core/session_id.h"
 #include "components/sessions/core/session_types.h"
 #include "content/public/browser/navigation_details.h"
 #include "content/public/browser/navigation_entry.h"
 #include "content/public/browser/restore_type.h"
 #include "content/public/browser/session_storage_namespace.h"
 #include "content/public/browser/storage_partition.h"
 #include "content/public/browser/web_contents.h"
 #include "weblayer/browser/browser_context_impl.h"
 #include "weblayer/browser/browser_impl.h"
 #include "weblayer/browser/persistence/browser_persistence_common.h"
 #include "weblayer/browser/profile_impl.h"
 #include "weblayer/browser/tab_impl.h"

 using sessions::ContentSerializedNavigationBuilder;
 using sessions::SerializedNavigationEntry;

 namespace weblayer {
 namespace {

 int GetIndexOfTab(BrowserImpl* browser, Tab* tab) {
   const std::vector<Tab*>& tabs = browser->GetTabs();
   auto iter = std::find(tabs.begin(), tabs.end(), tab);
   DCHECK(iter != tabs.end());
   return static_cast<int>(iter - tabs.begin());
 }

 }  // namespace

 // Every kWritesPerReset commands triggers recreating the file.
 constexpr int kWritesPerReset = 250;

 // BrowserPersister
 // -------------------------------------------------------------

 BrowserPersister::BrowserPersister(const base::FilePath& path,
                                    BrowserImpl* browser,
                                    const std::vector<uint8_t>& decryption_key)
     : browser_(browser),
       browser_session_id_(SessionID::NewUnique()),
       command_storage_manager_(
           std::make_unique<sessions::CommandStorageManager>(
               path,
               this,
               browser->profile()->GetBrowserContext()->IsOffTheRecord())),
       rebuild_on_next_save_(false),
       crypto_key_(decryption_key) {
   browser_->AddObserver(this);
   command_storage_manager_->GetCurrentSessionCommands(
       base::BindOnce(&BrowserPersister::OnGotCurrentSessionCommands,
                      weak_factory_.GetWeakPtr()),
       decryption_key);
 }

 BrowserPersister::~BrowserPersister() {
   SaveIfNecessary();
   browser_->RemoveObserver(this);
 }

 void BrowserPersister::SaveIfNecessary() {
   if (command_storage_manager_->HasPendingSave())
     command_storage_manager_->Save();
 }

 const std::vector<uint8_t>& BrowserPersister::GetCryptoKey() const {
   return crypto_key_;
 }

 bool BrowserPersister::ShouldUseDelayedSave() {
   return true;
 }

 void BrowserPersister::OnWillSaveCommands() {
   if (!rebuild_on_next_save_)
     return;

   rebuild_on_next_save_ = false;
   command_storage_manager_->set_pending_reset(true);
   command_storage_manager_->ClearPendingCommands();
   tab_to_available_range_.clear();
   BuildCommandsForBrowser();
 }

 void BrowserPersister::OnGeneratedNewCryptoKey(
     const std::vector<uint8_t>& key) {
   crypto_key_ = key;
 }

 void BrowserPersister::OnTabAdded(Tab* tab) {
   auto* tab_impl = static_cast<TabImpl*>(tab);
   data_observer_.Add(tab_impl);
   content::WebContents* web_contents = tab_impl->web_contents();
   auto* tab_helper = sessions::SessionTabHelper::FromWebContents(web_contents);
   DCHECK(tab_helper);
   tab_helper->SetWindowID(browser_session_id_);

   // Record the association between the SessionStorageNamespace and the
   // tab.
   content::SessionStorageNamespace* session_storage_namespace =
       web_contents->GetController().GetDefaultSessionStorageNamespace();
   session_storage_namespace->SetShouldPersist(true);

   if (rebuild_on_next_save_)
     return;

   int index = GetIndexOfTab(browser_, tab);
   BuildCommandsForTab(static_cast<TabImpl*>(tab), index);
   const std::vector<Tab*>& tabs = browser_->GetTabs();
   for (int i = index + 1; i < static_cast<int>(tabs.size()); ++i) {
     ScheduleCommand(sessions::CreateSetTabIndexInWindowCommand(
         GetSessionIDForTab(tabs[i]), i));
   }
 }

 void BrowserPersister::OnTabRemoved(Tab* tab, bool active_tab_changed) {
   auto* tab_impl = static_cast<TabImpl*>(tab);
   data_observer_.Remove(tab_impl);
   // Allow the associated sessionStorage to get deleted; it won't be needed
   // in the session restore.
   content::WebContents* web_contents = tab_impl->web_contents();
   content::SessionStorageNamespace* session_storage_namespace =
       web_contents->GetController().GetDefaultSessionStorageNamespace();
   session_storage_namespace->SetShouldPersist(false);

   if (rebuild_on_next_save_)
     return;

   ScheduleCommand(sessions::CreateTabClosedCommand(GetSessionIDForTab(tab)));
   const std::vector<Tab*>& tabs = browser_->GetTabs();
   for (size_t i = 0; i < tabs.size(); ++i) {
     ScheduleCommand(sessions::CreateSetTabIndexInWindowCommand(
         GetSessionIDForTab(tabs[i]), i));
   }
   auto i = tab_to_available_range_.find(GetSessionIDForTab(tab));
   if (i != tab_to_available_range_.end())
     tab_to_available_range_.erase(i);
 }

 void BrowserPersister::OnActiveTabChanged(Tab* tab) {
   if (rebuild_on_next_save_)
     return;

   const int index = tab == nullptr ? -1 : GetIndexOfTab(browser_, tab);
   ScheduleCommand(sessions::CreateSetSelectedTabInWindowCommand(
       browser_session_id_, index));
 }

 void BrowserPersister::OnDataChanged(
     TabImpl* tab,
     const std::map<std::string, std::string>& data) {
   if (rebuild_on_next_save_)
     return;

   ScheduleCommand(
       sessions::CreateSetTabDataCommand(GetSessionIDForTab(tab), data));
 }

 void BrowserPersister::SetTabUserAgentOverride(
     const SessionID& window_id,
     const SessionID& tab_id,
     const sessions::SerializedUserAgentOverride& user_agent_override) {
   if (rebuild_on_next_save_)
     return;

   ScheduleCommand(sessions::CreateSetTabUserAgentOverrideCommand(
       tab_id, user_agent_override));
 }

 void BrowserPersister::SetSelectedNavigationIndex(const SessionID& window_id,
                                                   const SessionID& tab_id,
                                                   int index) {
   if (rebuild_on_next_save_)
     return;

   if (tab_to_available_range_.find(tab_id) != tab_to_available_range_.end()) {
     if (index < tab_to_available_range_[tab_id].first ||
         index > tab_to_available_range_[tab_id].second) {
       // The new index is outside the range of what we've archived, schedule
       // a reset.
       ScheduleRebuildOnNextSave();
       return;
     }
   }
   ScheduleCommand(
       sessions::CreateSetSelectedNavigationIndexCommand(tab_id, index));
 }

 void BrowserPersister::UpdateTabNavigation(
     const SessionID& window_id,
     const SessionID& tab_id,
     const SerializedNavigationEntry& navigation) {
   if (rebuild_on_next_save_)
     return;

   if (tab_to_available_range_.find(tab_id) != tab_to_available_range_.end()) {
     std::pair<int, int>& range = tab_to_available_range_[tab_id];
     range.first = std::min(navigation.index(), range.first);
     range.second = std::max(navigation.index(), range.second);
   }
   ScheduleCommand(CreateUpdateTabNavigationCommand(tab_id, navigation));
 }

 void BrowserPersister::TabNavigationPathPruned(const SessionID& window_id,
                                                const SessionID& tab_id,
                                                int index,
                                                int count) {
   if (rebuild_on_next_save_)
     return;

   DCHECK_GE(index, 0);
   DCHECK_GT(count, 0);

   // Update the range of available indices.
   if (tab_to_available_range_.find(tab_id) != tab_to_available_range_.end()) {
     std::pair<int, int>& range = tab_to_available_range_[tab_id];

     // if both range.first and range.second are also deleted.
     if (range.second >= index && range.second < index + count &&
         range.first >= index && range.first < index + count) {
       range.first = range.second = 0;
     } else {
       // Update range.first
       if (range.first >= index + count)
         range.first = range.first - count;
       else if (range.first >= index && range.first < index + count)
         range.first = index;

       // Update range.second
       if (range.second >= index + count)
         range.second = std::max(range.first, range.second - count);
       else if (range.second >= index && range.second < index + count)
         range.second = std::max(range.first, index - 1);
     }
   }

   return ScheduleCommand(
       sessions::CreateTabNavigationPathPrunedCommand(tab_id, index, count));
 }

 void BrowserPersister::TabNavigationPathEntriesDeleted(
     const SessionID& window_id,
     const SessionID& tab_id) {
   if (rebuild_on_next_save_)
     return;

   // Multiple tabs might be affected by this deletion, so the rebuild is
   // delayed until next save.
   rebuild_on_next_save_ = true;
   command_storage_manager_->StartSaveTimer();
 }

 void BrowserPersister::ScheduleRebuildOnNextSave() {
   rebuild_on_next_save_ = true;
   command_storage_manager_->StartSaveTimer();
 }

 void BrowserPersister::OnGotCurrentSessionCommands(
     std::vector<std::unique_ptr<sessions::SessionCommand>> commands) {
   ScheduleRebuildOnNextSave();

   RestoreBrowserState(browser_, std::move(commands));

   is_restore_in_progress_ = false;
   browser_->OnRestoreCompleted();
 }

 void BrowserPersister::BuildCommandsForTab(TabImpl* tab, int index_in_browser) {
   command_storage_manager_->AppendRebuildCommands(
       BuildCommandsForTabConfiguration(browser_session_id_, tab,
                                        index_in_browser));

   const SessionID& session_id = GetSessionIDForTab(tab);
   content::NavigationController& controller =
       tab->web_contents()->GetController();
   const int current_index = controller.GetCurrentEntryIndex();
   const int min_index =
       std::max(current_index - sessions::gMaxPersistNavigationCount, 0);
   const int max_index =
       std::min(current_index + sessions::gMaxPersistNavigationCount,
                controller.GetEntryCount());
   const int pending_index = controller.GetPendingEntryIndex();
   tab_to_available_range_[session_id] =
       std::pair<int, int>(min_index, max_index);

   for (int i = min_index; i < max_index; ++i) {
     content::NavigationEntry* entry = (i == pending_index)
                                           ? controller.GetPendingEntry()
                                           : controller.GetEntryAtIndex(i);
     DCHECK(entry);
     const SerializedNavigationEntry navigation =
         ContentSerializedNavigationBuilder::FromNavigationEntry(i, entry);
     command_storage_manager_->AppendRebuildCommand(
         CreateUpdateTabNavigationCommand(session_id, navigation));
   }
   command_storage_manager_->AppendRebuildCommand(
       sessions::CreateSetSelectedNavigationIndexCommand(session_id,
                                                         current_index));

   // Record the association between the sessionStorage namespace and the tab.
   content::SessionStorageNamespace* session_storage_namespace =
       controller.GetDefaultSessionStorageNamespace();
   ScheduleCommand(sessions::CreateSessionStorageAssociatedCommand(
       session_id, session_storage_namespace->id()));
 }

 void BrowserPersister::BuildCommandsForBrowser() {
   // This is necessary for BrowserPersister to restore the browser. The type is
   // effectively ignored.
   command_storage_manager_->AppendRebuildCommand(
       sessions::CreateSetWindowTypeCommand(
           browser_session_id_,
           sessions::SessionWindow::WindowType::TYPE_NORMAL));

   int active_index = -1;
   int tab_index = 0;
   for (Tab* tab : browser_->GetTabs()) {
     BuildCommandsForTab(static_cast<TabImpl*>(tab), tab_index);
     if (tab == browser_->GetActiveTab())
       active_index = tab_index;
     ++tab_index;
   }

   command_storage_manager_->AppendRebuildCommand(
       sessions::CreateSetSelectedTabInWindowCommand(browser_session_id_,
                                                     active_index));
 }

 void BrowserPersister::ScheduleCommand(
     std::unique_ptr<sessions::SessionCommand> command) {
   DCHECK(command);
   if (ReplacePendingCommand(command_storage_manager_.get(), &command))
     return;
   command_storage_manager_->ScheduleCommand(std::move(command));
   if (command_storage_manager_->commands_since_reset() >= kWritesPerReset)
     ScheduleRebuildOnNextSave();
 }

 }  // namespace weblayer
	// Copyright 2020 The Chromium Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include "weblayer/browser/persistence/browser_persister.h"

	#include <stddef.h>

	#include <algorithm>
	#include <utility>
	#include <vector>

	#include "base/bind.h"
	#include "components/sessions/content/content_serialized_navigation_builder.h"
	#include "components/sessions/content/session_tab_helper.h"
	#include "components/sessions/core/command_storage_manager.h"
	#include "components/sessions/core/session_command.h"
	#include "components/sessions/core/session_constants.h"
	#include "components/sessions/core/session_id.h"
	#include "components/sessions/core/session_types.h"
	#include "content/public/browser/navigation_details.h"
	#include "content/public/browser/navigation_entry.h"
	#include "content/public/browser/restore_type.h"
	#include "content/public/browser/session_storage_namespace.h"
	#include "content/public/browser/storage_partition.h"
	#include "content/public/browser/web_contents.h"
	#include "weblayer/browser/browser_context_impl.h"
	#include "weblayer/browser/browser_impl.h"
	#include "weblayer/browser/persistence/browser_persistence_common.h"
	#include "weblayer/browser/profile_impl.h"
	#include "weblayer/browser/tab_impl.h"

	using sessions::ContentSerializedNavigationBuilder;
	using sessions::SerializedNavigationEntry;

	namespace weblayer {
	namespace {

	int GetIndexOfTab(BrowserImpl* browser, Tab* tab) {
	const std::vector<Tab*>& tabs = browser->GetTabs();
	auto iter = std::find(tabs.begin(), tabs.end(), tab);
	DCHECK(iter != tabs.end());
	return static_cast<int>(iter - tabs.begin());
	}

	} // namespace

	// Every kWritesPerReset commands triggers recreating the file.
	constexpr int kWritesPerReset = 250;

	// BrowserPersister
	// -------------------------------------------------------------

	BrowserPersister::BrowserPersister(const base::FilePath& path,
	BrowserImpl* browser,
	const std::vector<uint8_t>& decryption_key)
	: browser_(browser),
	browser_session_id_(SessionID::NewUnique()),
	command_storage_manager_(
	std::make_unique<sessions::CommandStorageManager>(
	path,
	this,
	browser->profile()->GetBrowserContext()->IsOffTheRecord())),
	rebuild_on_next_save_(false),
	crypto_key_(decryption_key) {
	browser_->AddObserver(this);
	command_storage_manager_->GetCurrentSessionCommands(
	base::BindOnce(&BrowserPersister::OnGotCurrentSessionCommands,
	weak_factory_.GetWeakPtr()),
	decryption_key);
	}

	BrowserPersister::~BrowserPersister() {
	SaveIfNecessary();
	browser_->RemoveObserver(this);
	}

	void BrowserPersister::SaveIfNecessary() {
	if (command_storage_manager_->HasPendingSave())
	command_storage_manager_->Save();
	}

	const std::vector<uint8_t>& BrowserPersister::GetCryptoKey() const {
	return crypto_key_;
	}

	bool BrowserPersister::ShouldUseDelayedSave() {
	return true;
	}

	void BrowserPersister::OnWillSaveCommands() {
	if (!rebuild_on_next_save_)
	return;

	rebuild_on_next_save_ = false;
	command_storage_manager_->set_pending_reset(true);
	command_storage_manager_->ClearPendingCommands();
	tab_to_available_range_.clear();
	BuildCommandsForBrowser();
	}

	void BrowserPersister::OnGeneratedNewCryptoKey(
	const std::vector<uint8_t>& key) {
	crypto_key_ = key;
	}

	void BrowserPersister::OnTabAdded(Tab* tab) {
	auto* tab_impl = static_cast<TabImpl*>(tab);
	data_observer_.Add(tab_impl);
	content::WebContents* web_contents = tab_impl->web_contents();
	auto* tab_helper = sessions::SessionTabHelper::FromWebContents(web_contents);
	DCHECK(tab_helper);
	tab_helper->SetWindowID(browser_session_id_);

	// Record the association between the SessionStorageNamespace and the
	// tab.
	content::SessionStorageNamespace* session_storage_namespace =
	web_contents->GetController().GetDefaultSessionStorageNamespace();
	session_storage_namespace->SetShouldPersist(true);

	if (rebuild_on_next_save_)
	return;

	int index = GetIndexOfTab(browser_, tab);
	BuildCommandsForTab(static_cast<TabImpl*>(tab), index);
	const std::vector<Tab*>& tabs = browser_->GetTabs();
	for (int i = index + 1; i < static_cast<int>(tabs.size()); ++i) {
	ScheduleCommand(sessions::CreateSetTabIndexInWindowCommand(
	GetSessionIDForTab(tabs[i]), i));
	}
	}

	void BrowserPersister::OnTabRemoved(Tab* tab, bool active_tab_changed) {
	auto* tab_impl = static_cast<TabImpl*>(tab);
	data_observer_.Remove(tab_impl);
	// Allow the associated sessionStorage to get deleted; it won't be needed
	// in the session restore.
	content::WebContents* web_contents = tab_impl->web_contents();
	content::SessionStorageNamespace* session_storage_namespace =
	web_contents->GetController().GetDefaultSessionStorageNamespace();
	session_storage_namespace->SetShouldPersist(false);

	if (rebuild_on_next_save_)
	return;

	ScheduleCommand(sessions::CreateTabClosedCommand(GetSessionIDForTab(tab)));
	const std::vector<Tab*>& tabs = browser_->GetTabs();
	for (size_t i = 0; i < tabs.size(); ++i) {
	ScheduleCommand(sessions::CreateSetTabIndexInWindowCommand(
	GetSessionIDForTab(tabs[i]), i));
	}
	auto i = tab_to_available_range_.find(GetSessionIDForTab(tab));
	if (i != tab_to_available_range_.end())
	tab_to_available_range_.erase(i);
	}

	void BrowserPersister::OnActiveTabChanged(Tab* tab) {
	if (rebuild_on_next_save_)
	return;

	const int index = tab == nullptr ? -1 : GetIndexOfTab(browser_, tab);
	ScheduleCommand(sessions::CreateSetSelectedTabInWindowCommand(
	browser_session_id_, index));
	}

	void BrowserPersister::OnDataChanged(
	TabImpl* tab,
	const std::map<std::string, std::string>& data) {
	if (rebuild_on_next_save_)
	return;

	ScheduleCommand(
	sessions::CreateSetTabDataCommand(GetSessionIDForTab(tab), data));
	}

	void BrowserPersister::SetTabUserAgentOverride(
	const SessionID& window_id,
	const SessionID& tab_id,
	const sessions::SerializedUserAgentOverride& user_agent_override) {
	if (rebuild_on_next_save_)
	return;

	ScheduleCommand(sessions::CreateSetTabUserAgentOverrideCommand(
	tab_id, user_agent_override));
	}

	void BrowserPersister::SetSelectedNavigationIndex(const SessionID& window_id,
	const SessionID& tab_id,
	int index) {
	if (rebuild_on_next_save_)
	return;

	if (tab_to_available_range_.find(tab_id) != tab_to_available_range_.end()) {
	if (index < tab_to_available_range_[tab_id].first \|\|
	index > tab_to_available_range_[tab_id].second) {
	// The new index is outside the range of what we've archived, schedule
	// a reset.
	ScheduleRebuildOnNextSave();
	return;
	}
	}
	ScheduleCommand(
	sessions::CreateSetSelectedNavigationIndexCommand(tab_id, index));
	}

	void BrowserPersister::UpdateTabNavigation(
	const SessionID& window_id,
	const SessionID& tab_id,
	const SerializedNavigationEntry& navigation) {
	if (rebuild_on_next_save_)
	return;

	if (tab_to_available_range_.find(tab_id) != tab_to_available_range_.end()) {
	std::pair<int, int>& range = tab_to_available_range_[tab_id];
	range.first = std::min(navigation.index(), range.first);
	range.second = std::max(navigation.index(), range.second);
	}
	ScheduleCommand(CreateUpdateTabNavigationCommand(tab_id, navigation));
	}

	void BrowserPersister::TabNavigationPathPruned(const SessionID& window_id,
	const SessionID& tab_id,
	int index,
	int count) {
	if (rebuild_on_next_save_)
	return;

	DCHECK_GE(index, 0);
	DCHECK_GT(count, 0);

	// Update the range of available indices.
	if (tab_to_available_range_.find(tab_id) != tab_to_available_range_.end()) {
	std::pair<int, int>& range = tab_to_available_range_[tab_id];

	// if both range.first and range.second are also deleted.
	if (range.second >= index && range.second < index + count &&
	range.first >= index && range.first < index + count) {
	range.first = range.second = 0;
	} else {
	// Update range.first
	if (range.first >= index + count)
	range.first = range.first - count;
	else if (range.first >= index && range.first < index + count)
	range.first = index;

	// Update range.second
	if (range.second >= index + count)
	range.second = std::max(range.first, range.second - count);
	else if (range.second >= index && range.second < index + count)
	range.second = std::max(range.first, index - 1);
	}
	}

	return ScheduleCommand(
	sessions::CreateTabNavigationPathPrunedCommand(tab_id, index, count));
	}

	void BrowserPersister::TabNavigationPathEntriesDeleted(
	const SessionID& window_id,
	const SessionID& tab_id) {
	if (rebuild_on_next_save_)
	return;

	// Multiple tabs might be affected by this deletion, so the rebuild is
	// delayed until next save.
	rebuild_on_next_save_ = true;
	command_storage_manager_->StartSaveTimer();
	}

	void BrowserPersister::ScheduleRebuildOnNextSave() {
	rebuild_on_next_save_ = true;
	command_storage_manager_->StartSaveTimer();
	}

	void BrowserPersister::OnGotCurrentSessionCommands(
	std::vector<std::unique_ptr<sessions::SessionCommand>> commands) {
	ScheduleRebuildOnNextSave();

	RestoreBrowserState(browser_, std::move(commands));

	is_restore_in_progress_ = false;
	browser_->OnRestoreCompleted();
	}

	void BrowserPersister::BuildCommandsForTab(TabImpl* tab, int index_in_browser) {
	command_storage_manager_->AppendRebuildCommands(
	BuildCommandsForTabConfiguration(browser_session_id_, tab,
	index_in_browser));

	const SessionID& session_id = GetSessionIDForTab(tab);
	content::NavigationController& controller =
	tab->web_contents()->GetController();
	const int current_index = controller.GetCurrentEntryIndex();
	const int min_index =
	std::max(current_index - sessions::gMaxPersistNavigationCount, 0);
	const int max_index =
	std::min(current_index + sessions::gMaxPersistNavigationCount,
	controller.GetEntryCount());
	const int pending_index = controller.GetPendingEntryIndex();
	tab_to_available_range_[session_id] =
	std::pair<int, int>(min_index, max_index);

	for (int i = min_index; i < max_index; ++i) {
	content::NavigationEntry* entry = (i == pending_index)
	? controller.GetPendingEntry()
	: controller.GetEntryAtIndex(i);
	DCHECK(entry);
	const SerializedNavigationEntry navigation =
	ContentSerializedNavigationBuilder::FromNavigationEntry(i, entry);
	command_storage_manager_->AppendRebuildCommand(
	CreateUpdateTabNavigationCommand(session_id, navigation));
	}
	command_storage_manager_->AppendRebuildCommand(
	sessions::CreateSetSelectedNavigationIndexCommand(session_id,
	current_index));

	// Record the association between the sessionStorage namespace and the tab.
	content::SessionStorageNamespace* session_storage_namespace =
	controller.GetDefaultSessionStorageNamespace();
	ScheduleCommand(sessions::CreateSessionStorageAssociatedCommand(
	session_id, session_storage_namespace->id()));
	}

	void BrowserPersister::BuildCommandsForBrowser() {
	// This is necessary for BrowserPersister to restore the browser. The type is
	// effectively ignored.
	command_storage_manager_->AppendRebuildCommand(
	sessions::CreateSetWindowTypeCommand(
	browser_session_id_,
	sessions::SessionWindow::WindowType::TYPE_NORMAL));

	int active_index = -1;
	int tab_index = 0;
	for (Tab* tab : browser_->GetTabs()) {
	BuildCommandsForTab(static_cast<TabImpl*>(tab), tab_index);
	if (tab == browser_->GetActiveTab())
	active_index = tab_index;
	++tab_index;
	}

	command_storage_manager_->AppendRebuildCommand(
	sessions::CreateSetSelectedTabInWindowCommand(browser_session_id_,
	active_index));
	}

	void BrowserPersister::ScheduleCommand(
	std::unique_ptr<sessions::SessionCommand> command) {
	DCHECK(command);
	if (ReplacePendingCommand(command_storage_manager_.get(), &command))
	return;
	command_storage_manager_->ScheduleCommand(std::move(command));
	if (command_storage_manager_->commands_since_reset() >= kWritesPerReset)
	ScheduleRebuildOnNextSave();
	}

	} // namespace weblayer