StackSamplingProfiler: collect partial bursts if the profiler is stopped early

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 5a6c3d0514d00a337d462f06e79c0e89ced5a249..9aad10fbeda7fb3d8b111092d6741a60c2b01940 100644
--- a/base/profiler/stack_sampling_profiler.h
+++ b/base/profiler/stack_sampling_profiler.h
@@ -51,8 +51,7 @@ class NativeStackSampler;
 //
 // When all call stack profiles are complete, or the profiler is stopped, the
 // completed callback is called from a thread created by the profiler with the
-// completed profiles. A profile is considered complete if all requested samples
-// were recorded for the profile (i.e. it was not stopped prematurely).
+// collected profiles.
 //
 // The results of the profiling are passed to the completed callback and consist
 // of a vector of CallStackProfiles. Each CallStackProfile corresponds to a
@@ -195,14 +194,15 @@ class BASE_EXPORT StackSamplingProfiler {
     void Stop();
 
    private:
-    // Collects a call stack profile from a single burst. Returns true if the
-    // profile was collected, or false if collection was stopped before it
-    // completed.
-    bool CollectProfile(CallStackProfile* profile, TimeDelta* elapsed_time);
+    // 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, |call_stack_profiles| will contain
-    // only full bursts.
+    // stopped. If stopped before complete, the last profile in
+    // |call_stack_profiles| may contain a partial burst.
     void CollectProfiles(CallStackProfiles* profiles);
 
     scoped_ptr<NativeStackSampler> native_sampler_;