Add StateOn{Moderate,Critical}NotificationReceived metrics

base/memory/memory_coordinator_client.h

Index: base/memory/memory_coordinator_client.h
diff --git a/base/memory/memory_coordinator_client.h b/base/memory/memory_coordinator_client.h
index 7d4681eed0ab270bfc8b9f8b98139bb28ae9db84..f9694dfba408d62cf6760d410cd0cbf454456bb1 100644
--- a/base/memory/memory_coordinator_client.h
+++ b/base/memory/memory_coordinator_client.h
@@ -22,7 +22,7 @@ namespace base {
 // MemoryState is an indicator that processes can use to guide their memory
 // allocation policies. For example, a process that receives the suspended
 // state can use that as as signal to drop memory caches.

[Ilya Sherman, 2016/11/07 19:28:51]

Please document that this enum is used to back an UMA histogram, and therefore
should be treated as append-only.

[bashi, 2016/11/08 00:33:35]

Done.

-enum class MemoryState {
+enum class MemoryState : int {
   // The state is unknown.
   UNKNOWN = -1,
   // No memory constraints.
@@ -38,6 +38,8 @@ enum class MemoryState {
   SUSPENDED = 2,
 };
 
+const int kMemoryStateMax = static_cast<int>(MemoryState::SUSPENDED) + 1;
+
 // Returns a string representation of MemoryState.
 BASE_EXPORT const char* MemoryStateToString(MemoryState state);