Make ProfileSyncService a client of memory coordinator

components/browser_sync/profile_sync_service.cc

Index: components/browser_sync/profile_sync_service.cc
diff --git a/components/browser_sync/profile_sync_service.cc b/components/browser_sync/profile_sync_service.cc
index 0b9152f3ca5e0f83cbf97a5e9fe344a67dbaac3c..f127e2ffca21796fd68e60d61b7c3a6171dc07f2 100644
--- a/components/browser_sync/profile_sync_service.cc
+++ b/components/browser_sync/profile_sync_service.cc
@@ -16,6 +16,7 @@
 #include "base/feature_list.h"
 #include "base/files/file_util.h"
 #include "base/logging.h"
+#include "base/memory/memory_coordinator_client_registry.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/metrics/histogram.h"
@@ -239,6 +240,8 @@ ProfileSyncService::ProfileSyncService(InitParams init_params)
       current_version.substr(0, current_version.find('.'))) {
     passphrase_prompt_triggered_by_version_ = true;
   }
+
+  base::MemoryCoordinatorClientRegistry::GetInstance()->Register(this);
 }
 
 ProfileSyncService::~ProfileSyncService() {
@@ -247,6 +250,7 @@ ProfileSyncService::~ProfileSyncService() {
   sync_prefs_.RemoveSyncPrefObserver(this);
   // Shutdown() should have been called before destruction.
   CHECK(!backend_initialized_);
+  base::MemoryCoordinatorClientRegistry::GetInstance()->Unregister(this);
 }
 
 bool ProfileSyncService::CanSyncStart() const {
@@ -2445,11 +2449,33 @@ void ProfileSyncService::OnMemoryPressure(
     base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level) {
   if (memory_pressure_level ==
       base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL) {
-    sync_prefs_.SetMemoryPressureWarningCount(
-        sync_prefs_.GetMemoryPressureWarningCount() + 1);
+    IncrementMemoryPressureWarningCount();
+  }
+}
+
+void ProfileSyncService::OnMemoryStateChange(base::MemoryState state) {
+  // TODO(hajimehoshi): Adjust the size of this memory usage according to
+  // |state|. ProfileSyncService doesn't have a feature to limit memory usage at
+  // present.
+  switch (state) {
+    case base::MemoryState::NORMAL:
+      break;
+    case base::MemoryState::THROTTLED:
+      IncrementMemoryPressureWarningCount();
+      break;
+    case base::MemoryState::SUSPENDED:
+      // Note: Not supported at present. Fall through.
+    case base::MemoryState::UNKNOWN:
+      NOTREACHED();
+      break;
   }
 }
 
+void ProfileSyncService::IncrementMemoryPressureWarningCount() {
+  sync_prefs_.SetMemoryPressureWarningCount(
+      sync_prefs_.GetMemoryPressureWarningCount() + 1);

[bashi, 2016/10/03 23:26:53]

Do we use the warning count to change behavior of ProfileSyncService or other
classes? In other words, is this purely for calculating statistics? If so,
Making ProfileSyncService be a MCC wouldn't make much sense IMO. Maybe we just
leave this MPL and remove later.

+}
+
 void ProfileSyncService::ReportPreviousSessionMemoryWarningCount() {
   int warning_received = sync_prefs_.GetMemoryPressureWarningCount();