Drop GCMStore account mappings once the account ID is migrated to Gaia ID

This CL removes the account mappings from the GCMStoreImpl during the
migration of the CoreAccountId from email to a Gaia ID. This is required
as the key of account mapping map stored on disk which was based on the
email does not correspond to the account ID once the identity manager
starts using Gaia IDs as the identifiers of an account.

Bug: 1028505

Change-Id: Ie4470d4f36a1fc7e15d488daf1ca5919932fd02b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1954020
Reviewed-by: Alex Ilin <[email protected]>
Reviewed-by: David Roger <[email protected]>
Reviewed-by: Peter Beverloo <[email protected]>
Commit-Queue: Mihai Sardarescu <[email protected]>
Cr-Commit-Position: refs/heads/master@{#723384}
diff --git a/chrome/browser/browser_process_impl.cc b/chrome/browser/browser_process_impl.cc
index 554dacc4..2a448f4 100644
--- a/chrome/browser/browser_process_impl.cc
+++ b/chrome/browser/browser_process_impl.cc
@@ -1310,6 +1310,7 @@
 
   gcm_driver_ = gcm::CreateGCMDriverDesktop(
       base::WrapUnique(new gcm::GCMClientFactory), local_state(), store_path,
+      /*remove_account_mappings_with_email_key=*/false,
       base::BindRepeating(&RequestProxyResolvingSocketFactory),
       system_network_context_manager()->GetSharedURLLoaderFactory(),
       content::GetNetworkConnectionTracker(), chrome::GetChannel(),