Add tests for Chrome Stability Metrics.

chrome/browser/metrics/chrome_stability_metrics_provider.h

Index: chrome/browser/metrics/chrome_stability_metrics_provider.h
diff --git a/chrome/browser/metrics/chrome_stability_metrics_provider.h b/chrome/browser/metrics/chrome_stability_metrics_provider.h
index 94da7d2cbbfc41e99205ce8ef07fd72a297d612d..d3c3a80050fa729921fce2283cb35170e0510758 100644
--- a/chrome/browser/metrics/chrome_stability_metrics_provider.h
+++ b/chrome/browser/metrics/chrome_stability_metrics_provider.h
@@ -6,6 +6,7 @@
 #define CHROME_BROWSER_METRICS_CHROME_STABILITY_METRICS_PROVIDER_H_
 
 #include "base/basictypes.h"
+#include "base/gtest_prod_util.h"
 #include "base/metrics/user_metrics.h"
 #include "base/process/kill.h"
 #include "components/metrics/metrics_provider.h"
@@ -20,6 +21,8 @@ class RenderProcessHost;
 class WebContents;
 }
 
+class PrefService;
+
 // ChromeStabilityMetricsProvider gathers and logs Chrome-specific stability-
 // related metrics.
 class ChromeStabilityMetricsProvider
@@ -27,7 +30,7 @@ class ChromeStabilityMetricsProvider
       public content::BrowserChildProcessObserver,
       public content::NotificationObserver {
  public:
-  ChromeStabilityMetricsProvider();
+  explicit ChromeStabilityMetricsProvider(PrefService* local_state);
   ~ChromeStabilityMetricsProvider() override;
 
   // metrics::MetricsDataProvider:
@@ -41,6 +44,11 @@ class ChromeStabilityMetricsProvider
   static void RegisterPrefs(PrefRegistrySimple* registry);
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(ChromeStabilityMetricsProviderTest,
+                           BrowserChildProcessObserver);
+  FRIEND_TEST_ALL_PREFIXES(ChromeStabilityMetricsProviderTest,
+                           NotificationObserver);
+
   // content::NotificationObserver:
   void Observe(int type,
                const content::NotificationSource& source,
@@ -60,9 +68,17 @@ class ChromeStabilityMetricsProvider
                         base::TerminationStatus status,
                         int exit_code);
 
+  // Increment an Integer pref value specified by |path|

[Avi (use Gerrit), 2015/09/02 01:11:10]

. at the end of sentences

[Will Harris, 2015/09/02 15:57:53]

Done.

+  void IncrementPrefValue(const char* path);
+
+  // Increment a 64-bit Integer pref value specified by |path|

[Avi (use Gerrit), 2015/09/02 01:11:10]

ditto

[Will Harris, 2015/09/02 15:57:53]

Done.

+  void IncrementLongPrefsValue(const char* path);
+
   // Records a renderer process hang.
   void LogRendererHang();
 
+  PrefService* local_state_;
+
   // Registrar for receiving stability-related notifications.
   content::NotificationRegistrar registrar_;