Add StateOn{Moderate,Critical}NotificationReceived metrics

content/browser/memory/memory_coordinator.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/memory/memory_coordinator.h"
 
 #include "base/memory/memory_coordinator_client_registry.h"
+#include "base/metrics/histogram_macros.h"
 #include "content/public/browser/content_browser_client.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/common/content_client.h"
 #include "content/public/common/content_features.h"
 
 namespace content {
 
 // The implementation of MemoryCoordinatorHandle. See memory_coordinator.mojom
 // for the role of this class.
 class MemoryCoordinatorHandleImpl : public mojom::MemoryCoordinatorHandle {
@@ skipping 95 matching lines @@
 }
 
 mojom::MemoryState MemoryCoordinator::GetMemoryState(
     int render_process_id) const {
   auto iter = children_.find(render_process_id);
   if (iter == children_.end())
     return mojom::MemoryState::UNKNOWN;
   return iter->second.memory_state;
 }
 
+void MemoryCoordinator::RecordMemoryPressure(
+    base::MemoryPressureMonitor::MemoryPressureLevel level) {
+  int state = static_cast<int>(GetCurrentMemoryState());
+  switch (level) {
+    case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE:
+      UMA_HISTOGRAM_ENUMERATION(
+          "Memory.Coordinator.StateOnModerateNotificationReceived",
+          state, base::kMemoryStateMax);
+      break;
+    case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL:
+      UMA_HISTOGRAM_ENUMERATION(
+          "Memory.Coordinator.StateOnCriticalNotificationReceived",
+          state, base::kMemoryStateMax);
+      break;
+    case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE:
+      // Fall through
+    default:

[Ilya Sherman, 2016/11/07 19:28:52]

nit: It's generally best to omit the default case, and instead to list each
possible case explicitly.  That way, if a new enum constant is ever added, the
author will need to make a conscious decision for how to handle it here.

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

Done.

+      NOTREACHED();
+  }
+}
+
 void MemoryCoordinator::EnableFeaturesForTesting() {
   base::FeatureList::ClearInstanceForTesting();
   std::unique_ptr<base::FeatureList> feature_list(new base::FeatureList);
   feature_list->InitializeFromCommandLine(features::kMemoryCoordinator.name,
                                           "");
   base::FeatureList::SetInstance(std::move(feature_list));
 }
 
 base::MemoryState MemoryCoordinator::GetCurrentMemoryState() const {
   return base::MemoryState::UNKNOWN;
@@ skipping 51 matching lines @@
 
 MemoryCoordinator::ChildInfo::ChildInfo() {}
 
 MemoryCoordinator::ChildInfo::ChildInfo(const ChildInfo& rhs) {
   // This is a nop, but exists for compatibility with STL containers.
 }
 
 MemoryCoordinator::ChildInfo::~ChildInfo() {}
 
 }  // namespace content