Add UMA data for memory pressure warning received for sync

chrome/browser/sync/profile_sync_service.cc

Index: chrome/browser/sync/profile_sync_service.cc
diff --git a/chrome/browser/sync/profile_sync_service.cc b/chrome/browser/sync/profile_sync_service.cc
index 2ac3deed199641b1b73d1e363b6f6284ebfac33c..bf4600189a8021a1bb3d6946de7a15c6ee27ed12 100644
--- a/chrome/browser/sync/profile_sync_service.cc
+++ b/chrome/browser/sync/profile_sync_service.cc
@@ -365,6 +365,8 @@ void ProfileSyncService::Initialize() {
   DCHECK(!running_rollback);
 #endif
 
+  memory_pressure_listener_.reset(new base::MemoryPressureListener(base::Bind(
+      &ProfileSyncService::OnMemoryPressure, weak_factory_.GetWeakPtr())));
   startup_controller_->Reset(GetRegisteredDataTypes());
   startup_controller_->TryStart();
 }
@@ -702,6 +704,8 @@ void ProfileSyncService::StartUpSlowBackendComponents(
   InitializeBackend(ShouldDeleteSyncFolder());
 
   UpdateFirstSyncTimePref();
+
+  CheckPreviousShutdownMemoryWarning();
 }
 
 void ProfileSyncService::OnGetTokenSuccess(
@@ -912,6 +916,8 @@ void ProfileSyncService::ShutdownImpl(syncer::ShutdownReason reason) {
     UpdateAuthErrorState(GoogleServiceAuthError::AuthErrorNone());
 
   NotifyObservers();
+
+  sync_prefs_.SetCurrentShutdown(false);

[stanisc, 2015/05/15 20:31:04]

Please add comment explaining this.

[Gang Wu, 2015/05/15 21:13:46]

Done.

 }
 
 void ProfileSyncService::DisableForUser() {
@@ -2720,3 +2726,28 @@ void ProfileSyncService::RemoveClientFromServer() const {
         access_token_, cache_guid, birthday);
   }
 }
+
+void ProfileSyncService::OnMemoryPressure(
+    base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level) {
+  if (memory_pressure_level ==
+      base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL) {
+    sync_prefs_.SetMemoryPressure(sync_prefs_.GetMemoryPressure() + 1);

[stanisc, 2015/05/15 20:31:04]

Looking at function names, GetMemoryPressure and SetMemoryPressure, I expected
them to return some sort of pressure level. From this code it looks like these
are counters of received warnings. Consider renaming these functions to reflect
that.
How about GetMemoryPressureWarningCount and SetMemoryPressureWarningCount?

[Gang Wu, 2015/05/15 21:13:46]

Done.

+  }
+}
+
+void ProfileSyncService::CheckPreviousShutdownMemoryWarning() {
+  int warning_received = sync_prefs_.GetMemoryPressure();
+
+  if (-1 != warning_received) {
+  // -1 means it is new client

[stanisc, 2015/05/15 20:31:04]

Indent this comment and add "." at the end.

[Gang Wu, 2015/05/15 21:13:46]

Done.

+    if (sync_prefs_.IsPreviousCrashed()) {
+      UMA_HISTOGRAM_COUNTS("Sync.MemoryPressureWarningBeforeCrash",
+                           warning_received);
+    } else {
+      UMA_HISTOGRAM_COUNTS("Sync.MemoryPressureWarningwithoutCrash",

[stanisc, 2015/05/15 20:31:04]

without should start with capital W

[Gang Wu, 2015/05/15 21:13:46]

Done.

+                           warning_received);
+    }
+  }
+  sync_prefs_.SetMemoryPressure(0);
+  sync_prefs_.SetCurrentShutdown(true);
+}