Don't create startup/shutdown watchers on Android.

StartupTimeBomb does nothing on Android (see crrev.com/672973002), and
ShutdownWatcherHelper is useless because on Android Chrome never shuts
down cleanly (it's killed by the OS).

This CL ifdefs out usages of StartupTimeBomb and ShutdownWatcherHelper
on Android.

Bug: 366699
Change-Id: I192bb86c794ef2423a7c32ef70c4a4eea35a64c0
Reviewed-on: https://chromium-review.googlesource.com/1028480
Commit-Queue: Dmitry Skiba <[email protected]>
Reviewed-by: Jochen Eisinger <[email protected]>
Reviewed-by: Gabriel Charette <[email protected]>
Reviewed-by: Alexei Svitkine <[email protected]>
Cr-Commit-Position: refs/heads/master@{#555456}
diff --git a/chrome/browser/chrome_browser_main.h b/chrome/browser/chrome_browser_main.h
index 8c745da..fefb5b7 100644
--- a/chrome/browser/chrome_browser_main.h
+++ b/chrome/browser/chrome_browser_main.h
@@ -147,6 +147,9 @@
   const base::CommandLine& parsed_command_line_;
   int result_code_;
 
+  ChromeBrowserFieldTrials browser_field_trials_;
+
+#if !defined(OS_ANDROID)
   // Create StartupTimeBomb object for watching jank during startup.
   std::unique_ptr<StartupTimeBomb> startup_watcher_;
 
@@ -155,11 +158,8 @@
   // it is destroyed last.
   std::unique_ptr<ShutdownWatcherHelper> shutdown_watcher_;
 
-  ChromeBrowserFieldTrials browser_field_trials_;
-
-#if !defined(OS_ANDROID)
   std::unique_ptr<WebUsbDetector> web_usb_detector_;
-#endif
+#endif  // !defined(OS_ANDROID)
 
   // Vector of additional ChromeBrowserMainExtraParts.
   // Parts are deleted in the inverse order they are added.