Enable startup profiling by Win x64 stack sampling profiler

components/metrics/call_stack_profile_metrics_provider.h

Index: components/metrics/call_stack_profile_metrics_provider.h
diff --git a/components/metrics/call_stack_profile_metrics_provider.h b/components/metrics/call_stack_profile_metrics_provider.h
index a2bb0f85a31bd8de9d0c53ad4d138ed1940aed4a..0cad6fd76fb30142506afa26ffc314b0bd4d2557 100644
--- a/components/metrics/call_stack_profile_metrics_provider.h
+++ b/components/metrics/call_stack_profile_metrics_provider.h
@@ -7,7 +7,10 @@
 
 #include <vector>
 
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "base/profiler/stack_sampling_profiler.h"
+#include "base/synchronization/lock.h"

[Ilya Sherman, 2015/03/24 21:07:55]

nit: No longer needed.

[Mike Wittman, 2015/03/24 22:40:59]

Done.

 #include "components/metrics/metrics_provider.h"
 
 namespace metrics {
@@ -20,6 +23,8 @@ class CallStackProfileMetricsProvider : public MetricsProvider {
   ~CallStackProfileMetricsProvider() override;
 
   // MetricsProvider:
+  void OnRecordingEnabled() override;
+  void OnRecordingDisabled() override;
   void ProvideGeneralMetrics(ChromeUserMetricsExtension* uma_proto) override;
 
   // Uses |profiles| as the source data for the next invocation of
@@ -28,8 +33,28 @@ class CallStackProfileMetricsProvider : public MetricsProvider {
   void SetSourceProfilesForTesting(
       const std::vector<base::StackSamplingProfiler::Profile>& profiles);
 
+ protected:
+  // Finch field trial and group for reporting profiles. Provided here for test
+  // use.
+  static const char kFieldTrialName[];
+  static const char kReportProfilesGroupName[];

[Ilya Sherman, 2015/03/24 21:07:55]

Optional: Actually, an easier option for testing might be to expose a protected
method "virtual bool IsEnabled()" (or a more detailed name, if you prefer).  The
production implementation could test the field trial state, whereas the test
could just return true or false as desired.  That way, the test doesn't need to
worry about Finch integration at all.

[Mike Wittman, 2015/03/24 22:40:59]

Hmm, I'm not enthusiastic about the impact of that approach on the interface.
Providing a method to determine the enable state implies that state varies
per-object in the implementation, when in fact it's global.

+
  private:
-  std::vector<base::StackSamplingProfiler::Profile> source_profiles_for_test_;
+  // Returns true if reporting of profiles is enabled according to the
+  // controlling Finch field trial.
+  static bool IsSamplingProfilingReportingEnabled();
+
+  // Invoked by the profiler on another thread.
+  static void ReceiveCompletedProfiles(
+      scoped_refptr<base::MessageLoopProxy> message_loop,

[Ilya Sherman, 2015/03/24 21:07:55]

nit: Forward-declare the MessageLoopProxy class?

[Mike Wittman, 2015/03/24 22:40:59]

Done.

+      base::WeakPtr<CallStackProfileMetricsProvider> provider,
+      const std::vector<base::StackSamplingProfiler::Profile>& profiles);
+  void AppendCompletedProfiles(
+      const std::vector<base::StackSamplingProfiler::Profile>& profiles);
+
+  std::vector<base::StackSamplingProfiler::Profile> pending_profiles_;
+
+  base::WeakPtrFactory<CallStackProfileMetricsProvider> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(CallStackProfileMetricsProvider);
 };