Support parallel captures from the StackSamplingProfiler.

base/profiler/stack_sampling_profiler.h

Index: base/profiler/stack_sampling_profiler.h
diff --git a/base/profiler/stack_sampling_profiler.h b/base/profiler/stack_sampling_profiler.h
index 622f6e5764a5b4e59fbf0a6eed6c7d328d737fc3..d2db971c96f42812a2c624d69a796c77aa9578a8 100644
--- a/base/profiler/stack_sampling_profiler.h
+++ b/base/profiler/stack_sampling_profiler.h
@@ -221,6 +221,27 @@ class BASE_EXPORT StackSamplingProfiler {
   // whichever occurs first.
   void Stop();
 
+  // Stops all active profiles and cleans up any resources in anticipation of
+  // a shutdown of the current process.
+  static void Shutdown();
+
+  // Resets the "shutdown" state so that the sampling thread can be restarted.
+  static void UndoShutdownForTesting();
+
+  // Returns whether the sampling thread is currently running or not.
+  static bool IsSamplingThreadRunningForTesting();
+
+  // Sets the auto-shutdown delay time for the sampling thread, in ms. Set this
+  // to zero to disable it.
+  static void SetSamplingThreadIdleShutdownTimeForTesting(int shutdown_ms);
+
+  // Initiates an idle shutdown task, as though the idle timer had expired,
+  // causing the thread to exit if there are no more sampling tasks pending.
+  // This returns immediately. Watch IsSamplingThreadRunningForTesting() to
+  // know when the thread has exited, though it will never do so if it is
+  // not idle.
+  static void InitiateSamplingThreadIdleShutdownForTesting();
+
   // Set the current system state that is recorded with each captured stack
   // frame. This is thread-safe so can be called from anywhere. The parameter
   // value should be from an enumeration of the appropriate type with values
@@ -233,44 +254,7 @@ class BASE_EXPORT StackSamplingProfiler {
  private:
   // SamplingThread is a separate thread used to suspend and sample stacks from
   // the target thread.
-  class SamplingThread : public PlatformThread::Delegate {
-   public:
-    // Samples stacks using |native_sampler|. When complete, invokes
-    // |completed_callback| with the collected call stack profiles.
-    // |completed_callback| must be callable on any thread.
-    SamplingThread(std::unique_ptr<NativeStackSampler> native_sampler,
-                   const SamplingParams& params,
-                   const CompletedCallback& completed_callback);
-    ~SamplingThread() override;
-
-    // PlatformThread::Delegate:
-    void ThreadMain() override;
-
-    void Stop();
-
-   private:
-    // Collects |profile| from a single burst. If the profiler was stopped
-    // during collection, sets |was_stopped| and provides the set of samples
-    // collected up to that point.
-    void CollectProfile(CallStackProfile* profile, TimeDelta* elapsed_time,
-                        bool* was_stopped);
-
-    // Collects call stack profiles from all bursts, or until the sampling is
-    // stopped. If stopped before complete, the last profile in
-    // |call_stack_profiles| may contain a partial burst.
-    void CollectProfiles(CallStackProfiles* profiles);
-
-    std::unique_ptr<NativeStackSampler> native_sampler_;
-    const SamplingParams params_;
-
-    // If Stop() is called, it signals this event to force the sampling to
-    // terminate before all the samples specified in |params_| are collected.
-    WaitableEvent stop_event_;
-
-    const CompletedCallback completed_callback_;
-
-    DISALLOW_COPY_AND_ASSIGN(SamplingThread);
-  };
+  class SamplingThread;
 
   // Adds annotations to a Sample.
   static void RecordAnnotations(Sample* sample);
@@ -287,11 +271,11 @@ class BASE_EXPORT StackSamplingProfiler {
 
   const SamplingParams params_;
 
-  std::unique_ptr<SamplingThread> sampling_thread_;
-  PlatformThreadHandle sampling_thread_handle_;
-
   const CompletedCallback completed_callback_;
 
+  // An ID uniquely identifying this collection to the sampling thread.
+  int collection_id_ = -1;
+
   // Stored until it can be passed to the NativeStackSampler created in Start().
   NativeStackSamplerTestDelegate* const test_delegate_;