content: convert child process notifications to observer usage

chrome/browser/metrics/metrics_service.cc

Index: chrome/browser/metrics/metrics_service.cc
diff --git a/chrome/browser/metrics/metrics_service.cc b/chrome/browser/metrics/metrics_service.cc
index cb183c708f819b2f415242fb5eb37c650a480c91..fc1bded6c20496c6565a901f6ac62c0ac9f93147 100644
--- a/chrome/browser/metrics/metrics_service.cc
+++ b/chrome/browser/metrics/metrics_service.cc
@@ -532,10 +532,14 @@ MetricsService::MetricsService()
   scheduler_.reset(new MetricsReportingScheduler(callback));
   log_manager_.set_log_serializer(new MetricsLogSerializer());
   log_manager_.set_max_ongoing_log_store_size(kUploadLogAvoidRetransmitSize);
+
+  BrowserChildProcessObserver::Add(this);
 }
 
 MetricsService::~MetricsService() {
   DisableRecording();
+
+  BrowserChildProcessObserver::Remove(this);
 }
 
 void MetricsService::Start() {
@@ -676,18 +680,31 @@ void MetricsService::SetUpNotifications(
                  content::NotificationService::AllSources());
   registrar->Add(observer, content::NOTIFICATION_RENDERER_PROCESS_HANG,
                  content::NotificationService::AllSources());
-  registrar->Add(observer, content::NOTIFICATION_CHILD_PROCESS_HOST_CONNECTED,
-                 content::NotificationService::AllSources());
-  registrar->Add(observer, content::NOTIFICATION_CHILD_INSTANCE_CREATED,
-                 content::NotificationService::AllSources());
-  registrar->Add(observer, content::NOTIFICATION_CHILD_PROCESS_CRASHED,
-                 content::NotificationService::AllSources());
   registrar->Add(observer, chrome::NOTIFICATION_TEMPLATE_URL_SERVICE_LOADED,
                  content::NotificationService::AllSources());
   registrar->Add(observer, chrome::NOTIFICATION_OMNIBOX_OPENED_URL,
                  content::NotificationService::AllSources());
 }
 
+void MetricsService::BrowserChildProcessHostConnected(
+    const content::ChildProcessData& data) {
+  GetChildProcessStats(data).process_launches++;
+}
+
+void MetricsService::BrowserChildProcessCrashed(
+    const content::ChildProcessData& data) {
+  GetChildProcessStats(data).process_crashes++;
+  // Exclude plugin crashes from the count below because we report them via
+  // a separate UMA metric.
+  if (!IsPluginProcess(data.type))
+    IncrementPrefValue(prefs::kStabilityChildProcessCrashCount);
+}
+
+void MetricsService::BrowserChildProcessInstanceCreated(
+    const content::ChildProcessData& data) {
+  GetChildProcessStats(data).instances++;
+}
+
 void MetricsService::Observe(int type,
                              const content::NotificationSource& source,
                              const content::NotificationDetails& details) {
@@ -744,12 +761,6 @@ void MetricsService::Observe(int type,
       LogRendererHang();
       break;
 
-    case content::NOTIFICATION_CHILD_PROCESS_HOST_CONNECTED:
-    case content::NOTIFICATION_CHILD_PROCESS_CRASHED:
-    case content::NOTIFICATION_CHILD_INSTANCE_CREATED:
-      LogChildProcessChange(type, source, details);
-      break;
-
     case chrome::NOTIFICATION_TEMPLATE_URL_SERVICE_LOADED:
       LogKeywordCount(content::Source<TemplateURLService>(
           source)->GetTemplateURLs().size());
@@ -1763,42 +1774,12 @@ void MetricsService::LogPluginLoadingError(const base::FilePath& plugin_path) {
   stats.loading_errors++;
 }
 
-void MetricsService::LogChildProcessChange(
-    int type,
-    const content::NotificationSource& source,
-    const content::NotificationDetails& details) {
-  content::Details<ChildProcessData> child_details(details);
-  const string16& child_name = child_details->name;
-
-  if (child_process_stats_buffer_.find(child_name) ==
-      child_process_stats_buffer_.end()) {
-    child_process_stats_buffer_[child_name] =
-        ChildProcessStats(child_details->type);
-  }
-
-  ChildProcessStats& stats = child_process_stats_buffer_[child_name];
-  switch (type) {
-    case content::NOTIFICATION_CHILD_PROCESS_HOST_CONNECTED:
-      stats.process_launches++;
-      break;
-
-    case content::NOTIFICATION_CHILD_INSTANCE_CREATED:
-      stats.instances++;
-      break;
-
-    case content::NOTIFICATION_CHILD_PROCESS_CRASHED:
-      stats.process_crashes++;
-      // Exclude plugin crashes from the count below because we report them via
-      // a separate UMA metric.
-      if (!IsPluginProcess(child_details->type)) {
-        IncrementPrefValue(prefs::kStabilityChildProcessCrashCount);
-      }
-      break;
-
-    default:
-      NOTREACHED() << "Unexpected notification type " << type;
-      return;
-  }
+MetricsService::ChildProcessStats& MetricsService::GetChildProcessStats(
+    const content::ChildProcessData& data) {
+  const string16& child_name = data.name;
+  if (!ContainsKey(child_process_stats_buffer_, child_name))
+    child_process_stats_buffer_[child_name] = ChildProcessStats(data.type);
+  return child_process_stats_buffer_[child_name];
 }
 
 void MetricsService::LogKeywordCount(size_t keyword_count) {