Enable startup profiling by Win x64 stack sampling profiler

Collects stack samples at 10 Hz for 30 seconds at startup. Uploading of
samples to UMA is controlled by a Finch experiment.

This change moves to a callback-based mechanism for communicating
completed profiles to the metrics provider to avoid profiles lingering
in memory when reporting is disabled.

BUG=464929

Review URL: https://codereview.chromium.org/1029653002

Cr-Commit-Position: refs/heads/master@{#324175}

base/profiler/stack_sampling_profiler.cc

@@ -15,61 +15,102 @@
 
 namespace base {
 
-// PendingProfiles ------------------------------------------------------------
+// DefaultProfileProcessor ----------------------------------------------------
 
 namespace {
 
-// Thread-safe singleton class that stores collected call stack profiles waiting
-// to be processed.
-class PendingProfiles {
+// Singleton class responsible for providing the default processing for profiles
+// (i.e. for profiles generated by profilers without their own completed
+// callback).
+class DefaultProfileProcessor {
  public:
-  ~PendingProfiles();
+  using CompletedCallback = StackSamplingProfiler::CompletedCallback;
 
-  static PendingProfiles* GetInstance();
+  ~DefaultProfileProcessor();
 
-  // Appends |profiles| to |profiles_|. This function may be called on any
-  // thread.
-  void AppendProfiles(
-      const std::vector<StackSamplingProfiler::CallStackProfile>& profiles);
+  static DefaultProfileProcessor* GetInstance();
+
+  // Sets the callback to use for processing profiles captured without a
+  // per-profiler completed callback. Pending completed profiles are stored in
+  // this object until a non-null callback is provided here. This function is
+  // thread-safe.
+  void SetCompletedCallback(CompletedCallback callback);
+
+  // Processes |profiles|. This function is thread safe.
+  void ProcessProfiles(
+      const StackSamplingProfiler::CallStackProfiles& profiles);
+
+ private:
+  friend struct DefaultSingletonTraits<DefaultProfileProcessor>;
+
+  DefaultProfileProcessor();
 
   // Copies the pending profiles from |profiles_| into |profiles|, and clears
   // |profiles_|. This function may be called on any thread.
   void GetAndClearPendingProfiles(
-      std::vector<StackSamplingProfiler::CallStackProfile>* profiles);
+      StackSamplingProfiler::CallStackProfiles* profiles);
 
- private:
-  friend struct DefaultSingletonTraits<PendingProfiles>;
+  // Gets the current completed callback, with proper locking.
+  CompletedCallback GetCompletedCallback() const;
 
-  PendingProfiles();
+  mutable Lock callback_lock_;
+  CompletedCallback default_completed_callback_;
 
   Lock profiles_lock_;
-  std::vector<StackSamplingProfiler::CallStackProfile> profiles_;
+  StackSamplingProfiler::CallStackProfiles profiles_;
 
-  DISALLOW_COPY_AND_ASSIGN(PendingProfiles);
+  DISALLOW_COPY_AND_ASSIGN(DefaultProfileProcessor);
 };
 
-PendingProfiles::PendingProfiles() {}
-
-PendingProfiles::~PendingProfiles() {}
+DefaultProfileProcessor::~DefaultProfileProcessor() {}
 
 // static
-PendingProfiles* PendingProfiles::GetInstance() {
-  return Singleton<PendingProfiles>::get();
+DefaultProfileProcessor* DefaultProfileProcessor::GetInstance() {
+  return Singleton<DefaultProfileProcessor>::get();
 }
 
-void PendingProfiles::AppendProfiles(
-    const std::vector<StackSamplingProfiler::CallStackProfile>& profiles) {
-  AutoLock scoped_lock(profiles_lock_);
-  profiles_.insert(profiles_.end(), profiles.begin(), profiles.end());
+void DefaultProfileProcessor::SetCompletedCallback(CompletedCallback callback) {
+  {
+    AutoLock scoped_lock(callback_lock_);
+    default_completed_callback_ = callback;
+  }
+
+  if (!callback.is_null()) {
+    // Provide any pending profiles to the callback immediately.
+    StackSamplingProfiler::CallStackProfiles profiles;
+    GetAndClearPendingProfiles(&profiles);
+    if (!profiles.empty())
+      callback.Run(profiles);
+  }
+}
+
+void DefaultProfileProcessor::ProcessProfiles(
+    const StackSamplingProfiler::CallStackProfiles& profiles) {
+  CompletedCallback callback = GetCompletedCallback();
+
+  // Store pending profiles if we don't have a valid callback.
+  if (!callback.is_null()) {
+    callback.Run(profiles);
+  } else {
+    AutoLock scoped_lock(profiles_lock_);
+    profiles_.insert(profiles_.end(), profiles.begin(), profiles.end());
+  }
 }
 
-void PendingProfiles::GetAndClearPendingProfiles(
-    std::vector<StackSamplingProfiler::CallStackProfile>* profiles) {
+DefaultProfileProcessor::DefaultProfileProcessor() {}
+
+void DefaultProfileProcessor::GetAndClearPendingProfiles(
+    StackSamplingProfiler::CallStackProfiles* profiles) {
   profiles->clear();
 
   AutoLock scoped_lock(profiles_lock_);
   profiles_.swap(*profiles);
 }
+DefaultProfileProcessor::CompletedCallback
+DefaultProfileProcessor::GetCompletedCallback() const {
+  AutoLock scoped_lock(callback_lock_);
+  return default_completed_callback_;
+}
 
 }  // namespace
 
@@ -209,7 +250,16 @@ StackSamplingProfiler::StackSamplingProfiler(PlatformThreadId thread_id,
                                              const SamplingParams& params)
     : thread_id_(thread_id), params_(params) {}
 
-StackSamplingProfiler::~StackSamplingProfiler() {}
+StackSamplingProfiler::StackSamplingProfiler(PlatformThreadId thread_id,
+                                             const SamplingParams& params,
+                                             CompletedCallback callback)
+    : thread_id_(thread_id), params_(params), completed_callback_(callback) {}
+
+StackSamplingProfiler::~StackSamplingProfiler() {
+  Stop();
+  if (!sampling_thread_handle_.is_null())
+    PlatformThread::Join(sampling_thread_handle_);
+}
 
 void StackSamplingProfiler::Start() {
   scoped_ptr<NativeStackSampler> native_sampler =
@@ -217,14 +267,14 @@ void StackSamplingProfiler::Start() {
   if (!native_sampler)
     return;
 
+  CompletedCallback callback =
+      !completed_callback_.is_null() ? completed_callback_ :
+      Bind(&DefaultProfileProcessor::ProcessProfiles,
+           Unretained(DefaultProfileProcessor::GetInstance()));
   sampling_thread_.reset(
-      new SamplingThread(
-          native_sampler.Pass(), params_,
-          (custom_completed_callback_.is_null() ?
-           Bind(&PendingProfiles::AppendProfiles,
-                Unretained(PendingProfiles::GetInstance())) :
-           custom_completed_callback_)));
-  if (!PlatformThread::CreateNonJoinable(0, sampling_thread_.get()))
+      new SamplingThread(native_sampler.Pass(), params_, callback));
+  if (!PlatformThread::Create(0, sampling_thread_.get(),
+                              &sampling_thread_handle_))
     sampling_thread_.reset();
 }
 
@@ -234,8 +284,9 @@ void StackSamplingProfiler::Stop() {
 }
 
 // static
-void StackSamplingProfiler::GetPendingProfiles(CallStackProfiles* profiles) {
-  PendingProfiles::GetInstance()->GetAndClearPendingProfiles(profiles);
+void StackSamplingProfiler::SetDefaultCompletedCallback(
+    CompletedCallback callback) {
+  DefaultProfileProcessor::GetInstance()->SetCompletedCallback(callback);
 }
 
 // StackSamplingProfiler::Frame global functions ------------------------------

base/profiler/stack_sampling_profiler.h

@@ -34,11 +34,12 @@ class NativeStackSampler;
 //   base::StackSamplingProfiler profiler(base::PlatformThread::CurrentId()),
 //       params);
 //
-//   // To process the call stack profiles within Chrome rather than via UMA,
-//   // set a custom completed callback:
+//   // Or, to process the profiles within Chrome rather than via UMA, use a
+//   // custom completed callback:
 //   base::StackStackSamplingProfiler::CompletedCallback
 //       thread_safe_callback = ...;
-//   profiler.SetCustomCompletedCallback(thread_safe_callback);
+//   base::StackSamplingProfiler profiler(base::PlatformThread::CurrentId()),
+//       params, thread_safe_callback);
 //
 //   profiler.Start();
 //   // ... work being done on the target thread here ...
@@ -49,13 +50,13 @@ class NativeStackSampler;
 // altered as desired.
 //
 // When all call stack profiles are complete or the profiler is stopped, if the
-// custom completed callback was set it is called from the profiler thread 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). If no callback was set, the completed profiles are stored
-// internally and retrieved for UMA through GetPendingProfiles().
-// GetPendingProfiles() should never be called by other code; to retrieve
-// profiles for in-process processing, set a completed callback.
+// custom completed callback was set it 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).  If no callback was set, the default completed callback will be
+// called with the profiles. It is expected that the the default completed
+// callback is set by the metrics system to allow profiles to be provided via
+// UMA.
 //
 // The results of the profiling are passed to the completed callback and consist
 // of a vector of CallStackProfiles. Each CallStackProfile corresponds to a
@@ -164,8 +165,14 @@ class BASE_EXPORT StackSamplingProfiler {
   // thread-safe callback implementation.
   using CompletedCallback = Callback<void(const CallStackProfiles&)>;
 
+  // Creates a profiler that sends completed profiles to the default completed
+  // callback.
   StackSamplingProfiler(PlatformThreadId thread_id,
                         const SamplingParams& params);
+  // Creates a profiler that sends completed profiles to |completed_callback|.
+  StackSamplingProfiler(PlatformThreadId thread_id,
+                        const SamplingParams& params,
+                        CompletedCallback callback);
   ~StackSamplingProfiler();
 
   // Initializes the profiler and starts sampling.
@@ -176,19 +183,14 @@ class BASE_EXPORT StackSamplingProfiler {
   // specified in the SamplingParams are completed.
   void Stop();
 
-  // Moves all pending call stack profiles from internal storage to
-  // |profiles|. This function is thread safe.
+  // Sets a callback to process profiles collected by profiler instances without
+  // a completed callback. Profiles are queued internally until a non-null
+  // callback is provided to this function,
   //
-  // ***This is intended for use only by UMA.*** Callers who want to process the
-  // collected profiles should use SetCustomCompletedCallback.
-  static void GetPendingProfiles(CallStackProfiles* call_stack_profiles);
-
-  // By default, collected call stack profiles are stored internally and can be
-  // retrieved by GetPendingProfiles. If a callback is provided via this
-  // function, however, it is called with the collected profiles instead.
-  void set_custom_completed_callback(CompletedCallback callback) {
-    custom_completed_callback_ = callback;
-  }
+  // The callback is typically called on a thread created by the profiler.  If
+  // completed profiles are queued when set, however, it will also be called
+  // immediately on the calling thread.
+  static void SetDefaultCompletedCallback(CompletedCallback callback);
 
  private:
   // SamplingThread is a separate thread used to suspend and sample stacks from
@@ -226,7 +228,7 @@ class BASE_EXPORT StackSamplingProfiler {
     // terminate before all the samples specified in |params_| are collected.
     WaitableEvent stop_event_;
 
-    CompletedCallback completed_callback_;
+    const CompletedCallback completed_callback_;
 
     DISALLOW_COPY_AND_ASSIGN(SamplingThread);
   };
@@ -237,8 +239,9 @@ class BASE_EXPORT StackSamplingProfiler {
   const SamplingParams params_;
 
   scoped_ptr<SamplingThread> sampling_thread_;
+  PlatformThreadHandle sampling_thread_handle_;
 
-  CompletedCallback custom_completed_callback_;
+  const CompletedCallback completed_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(StackSamplingProfiler);
 };

chrome/browser/chrome_browser_main.cc

@@ -577,11 +577,14 @@ ChromeBrowserMainParts::ChromeBrowserMainParts(
       startup_watcher_(new StartupTimeBomb()),
       shutdown_watcher_(new ShutdownWatcherHelper()),
       browser_field_trials_(parameters.command_line),
+      sampling_profiler_(base::PlatformThread::CurrentId(),
+                         GetStartupSamplingParams()),
       profile_(NULL),
       run_message_loop_(true),
       notify_result_(ProcessSingleton::PROCESS_NONE),
       local_state_(NULL),
       restart_last_session_(false) {
+  sampling_profiler_.Start();
   // If we're running tests (ui_task is non-null).
   if (parameters.ui_task)
     browser_defaults::enable_help_app = false;
@@ -723,6 +726,19 @@ void ChromeBrowserMainParts::RecordBrowserStartupTime() {
   new LoadCompleteListener();
 }
 
+// static
+base::StackSamplingProfiler::SamplingParams
+ChromeBrowserMainParts::GetStartupSamplingParams() {
+  // Sample at 10Hz for 30 seconds.
+  base::StackSamplingProfiler::SamplingParams params;
+  params.initial_delay = base::TimeDelta::FromMilliseconds(0);
+  params.bursts = 1;
+  params.samples_per_burst = 300;
+  params.sampling_interval = base::TimeDelta::FromMilliseconds(100);
+  params.preserve_sample_ordering = false;
+  return params;
+}
+
 // -----------------------------------------------------------------------------
 // TODO(viettrungluu): move more/rest of BrowserMain() into BrowserMainParts.
 

chrome/browser/chrome_browser_main.h

@@ -8,6 +8,7 @@
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/field_trial.h"
+#include "base/profiler/stack_sampling_profiler.h"
 #include "base/tracked_objects.h"
 #include "chrome/browser/chrome_browser_field_trials.h"
 #include "chrome/browser/chrome_process_singleton.h"
@@ -109,10 +110,8 @@ class ChromeBrowserMainParts : public content::BrowserMainParts {
   // Record time from process startup to present time in an UMA histogram.
   void RecordBrowserStartupTime();
 
-  // Records a time value to an UMA histogram in the context of the
-  // PreReadExperiment field-trial. This also reports to the appropriate
-  // sub-histogram (_PreRead(Enabled|Disabled)).
-  void RecordPreReadExperimentTime(const char* name, base::TimeDelta time);
+  // Create parameters for sampling stacks during startup.
+  static base::StackSamplingProfiler::SamplingParams GetStartupSamplingParams();
 
   // Methods for Main Message Loop -------------------------------------------
 
@@ -148,6 +147,10 @@ class ChromeBrowserMainParts : public content::BrowserMainParts {
   // Parts are deleted in the inverse order they are added.
   std::vector<ChromeBrowserMainExtraParts*> chrome_extra_parts_;
 
+  // A profiler that periodically samples stack traces. Used to sample startup
+  // behavior.
+  base::StackSamplingProfiler sampling_profiler_;
+
   // Members initialized after / released before main_message_loop_ ------------
 
   scoped_ptr<BrowserProcessImpl> browser_process_;

components/metrics/call_stack_profile_metrics_provider.cc

@@ -8,8 +8,11 @@
 #include <map>
 #include <utility>
 
+#include "base/bind.h"
 #include "base/logging.h"
 #include "base/macros.h"
+#include "base/message_loop/message_loop_proxy.h"
+#include "base/metrics/field_trial.h"
 #include "base/profiler/stack_sampling_profiler.h"
 #include "components/metrics/metrics_hashes.h"
 #include "components/metrics/proto/chrome_user_metrics_extension.pb.h"
@@ -20,6 +23,12 @@ namespace metrics {
 
 namespace {
 
+// Accepts and ignores the completed profiles. Used when metrics reporting is
+// disabled.
+void IgnoreCompletedProfiles(
+    const StackSamplingProfiler::CallStackProfiles& profiles) {
+}
+
 // The protobuf expects the MD5 checksum prefix of the module name.
 uint64 HashModuleFilename(const base::FilePath& filename) {
   const base::FilePath::StringType basename = filename.BaseName().value();
@@ -104,30 +113,80 @@ void CopyProfileToProto(
   proto_profile->set_sampling_period_ms(
       profile.sampling_period.InMilliseconds());
 }
+
 }  // namespace
 
-CallStackProfileMetricsProvider::CallStackProfileMetricsProvider() {}
+const char CallStackProfileMetricsProvider::kFieldTrialName[] =
+    "StackProfiling";
+const char CallStackProfileMetricsProvider::kReportProfilesGroupName[] =
+    "Report profiles";
+
+CallStackProfileMetricsProvider::CallStackProfileMetricsProvider()
+    : weak_factory_(this) {
+}
+
+CallStackProfileMetricsProvider::~CallStackProfileMetricsProvider() {
+  StackSamplingProfiler::SetDefaultCompletedCallback(
+      StackSamplingProfiler::CompletedCallback());
+}
+
+void CallStackProfileMetricsProvider::OnRecordingEnabled() {
+  StackSamplingProfiler::SetDefaultCompletedCallback(
+      base::Bind(&CallStackProfileMetricsProvider::ReceiveCompletedProfiles,
+                 base::MessageLoopProxy::current(),
+                 weak_factory_.GetWeakPtr()));
+}
 
-CallStackProfileMetricsProvider::~CallStackProfileMetricsProvider() {}
+void CallStackProfileMetricsProvider::OnRecordingDisabled() {
+  StackSamplingProfiler::SetDefaultCompletedCallback(
+      base::Bind(&IgnoreCompletedProfiles));
+  pending_profiles_.clear();
+}
 
 void CallStackProfileMetricsProvider::ProvideGeneralMetrics(
     ChromeUserMetricsExtension* uma_proto) {
-  std::vector<StackSamplingProfiler::CallStackProfile> profiles;
-  if (!source_profiles_for_test_.empty())
-    profiles.swap(source_profiles_for_test_);
-  else
-    StackSamplingProfiler::GetPendingProfiles(&profiles);
-
-  for (const StackSamplingProfiler::CallStackProfile& profile : profiles) {
+  DCHECK(IsSamplingProfilingReportingEnabled() || pending_profiles_.empty());
+  for (const StackSamplingProfiler::CallStackProfile& profile :
+       pending_profiles_) {
     CallStackProfile* call_stack_profile =
         uma_proto->add_sampled_profile()->mutable_call_stack_profile();
     CopyProfileToProto(profile, call_stack_profile);
   }
+  pending_profiles_.clear();
 }
 
-void CallStackProfileMetricsProvider::SetSourceProfilesForTesting(
+void CallStackProfileMetricsProvider::AppendSourceProfilesForTesting(
     const std::vector<StackSamplingProfiler::CallStackProfile>& profiles) {
-  source_profiles_for_test_ = profiles;
+  AppendCompletedProfiles(profiles);
+}
+
+// static
+bool CallStackProfileMetricsProvider::IsSamplingProfilingReportingEnabled() {
+  const std::string group_name = base::FieldTrialList::FindFullName(
+      CallStackProfileMetricsProvider::kFieldTrialName);
+  return group_name ==
+      CallStackProfileMetricsProvider::kReportProfilesGroupName;
+}
+
+// static
+// Posts a message back to our own thread to collect the profiles.
+void CallStackProfileMetricsProvider::ReceiveCompletedProfiles(
+    scoped_refptr<base::MessageLoopProxy> message_loop,
+    base::WeakPtr<CallStackProfileMetricsProvider> provider,
+    const StackSamplingProfiler::CallStackProfiles& profiles) {
+  message_loop->PostTask(
+      FROM_HERE,
+      base::Bind(&CallStackProfileMetricsProvider::AppendCompletedProfiles,
+                 provider, profiles));
+}
+
+void CallStackProfileMetricsProvider::AppendCompletedProfiles(
+    const StackSamplingProfiler::CallStackProfiles& profiles) {
+  // Don't bother to record profiles if reporting is not enabled.
+  if (IsSamplingProfilingReportingEnabled()) {
+    pending_profiles_.insert(pending_profiles_.end(), profiles.begin(),
+                             profiles.end());
+  }
 }
 
 }  // namespace metrics

components/metrics/call_stack_profile_metrics_provider.h

@@ -7,9 +7,15 @@
 
 #include <vector>
 
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "base/profiler/stack_sampling_profiler.h"
 #include "components/metrics/metrics_provider.h"
 
+namespace base {
+class MessageLoopProxy;
+}  // namespace base
+
 namespace metrics {
 class ChromeUserMetricsExtension;
 
@@ -20,18 +26,38 @@ 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
-  // ProvideGeneralMetrics, rather than sourcing them from the
-  // StackSamplingProfiler.
-  void SetSourceProfilesForTesting(
+  // Appends |profiles| for use by the next invocation of ProvideGeneralMetrics,
+  // rather than sourcing them from the StackSamplingProfiler.
+  void AppendSourceProfilesForTesting(
       const std::vector<base::StackSamplingProfiler::CallStackProfile>&
           profiles);
 
+ protected:
+  // Finch field trial and group for reporting profiles. Provided here for test
+  // use.
+  static const char kFieldTrialName[];
+  static const char kReportProfilesGroupName[];
+
  private:
-  std::vector<base::StackSamplingProfiler::CallStackProfile>
-      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,
+      base::WeakPtr<CallStackProfileMetricsProvider> provider,
+      const base::StackSamplingProfiler::CallStackProfiles& profiles);
+  void AppendCompletedProfiles(
+      const base::StackSamplingProfiler::CallStackProfiles& profiles);
+
+  base::StackSamplingProfiler::CallStackProfiles pending_profiles_;
+
+  base::WeakPtrFactory<CallStackProfileMetricsProvider> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(CallStackProfileMetricsProvider);
 };

components/metrics/call_stack_profile_metrics_provider_unittest.cc

@@ -4,9 +4,11 @@
 
 #include "components/metrics/call_stack_profile_metrics_provider.h"
 
+#include "base/metrics/field_trial.h"
 #include "base/profiler/stack_sampling_profiler.h"
 #include "base/strings/string_number_conversions.h"
 #include "components/metrics/proto/chrome_user_metrics_extension.pb.h"
+#include "components/variations/entropy_provider.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using base::StackSamplingProfiler;
@@ -17,8 +19,33 @@ using Sample = StackSamplingProfiler::Sample;
 
 namespace metrics {
 
+// This test fixture enables the field trial that
+// CallStackProfileMetricsProvider depends on to report profiles.
+class CallStackProfileMetricsProviderTest : public testing::Test {
+ public:
+  CallStackProfileMetricsProviderTest()
+      : field_trial_list_(new base::FieldTrialList(
+          new metrics::SHA1EntropyProvider("foo"))) {
+    base::FieldTrialList::CreateFieldTrial(
+        FieldTrialState::kFieldTrialName,
+        FieldTrialState::kReportProfilesGroupName);
+  }
+
+  ~CallStackProfileMetricsProviderTest() override {}
+
+ private:
+  // Exposes field trial/group names from the CallStackProfileMetricsProvider.
+  class FieldTrialState : public CallStackProfileMetricsProvider {
+   public:
+    using CallStackProfileMetricsProvider::kFieldTrialName;
+    using CallStackProfileMetricsProvider::kReportProfilesGroupName;
+  };
+
+  const scoped_ptr<base::FieldTrialList> field_trial_list_;
+};
+
 // Checks that all properties from multiple profiles are filled as expected.
-TEST(CallStackProfileMetricsProviderTest, MultipleProfiles) {
+TEST_F(CallStackProfileMetricsProviderTest, MultipleProfiles) {
   const uintptr_t module1_base_address = 0x1000;
   const uintptr_t module2_base_address = 0x2000;
   const uintptr_t module3_base_address = 0x3000;
@@ -165,7 +192,7 @@ TEST(CallStackProfileMetricsProviderTest, MultipleProfiles) {
   }
 
   CallStackProfileMetricsProvider provider;
-  provider.SetSourceProfilesForTesting(profiles);
+  provider.AppendSourceProfilesForTesting(profiles);
   ChromeUserMetricsExtension uma_proto;
   provider.ProvideGeneralMetrics(&uma_proto);
 
@@ -229,7 +256,7 @@ TEST(CallStackProfileMetricsProviderTest, MultipleProfiles) {
 
 // Checks that all duplicate samples are collapsed with
 // preserve_sample_ordering = false.
-TEST(CallStackProfileMetricsProviderTest, RepeatedStacksUnordered) {
+TEST_F(CallStackProfileMetricsProviderTest, RepeatedStacksUnordered) {
   const uintptr_t module_base_address = 0x1000;
 
   const Module modules[] = {
@@ -268,7 +295,7 @@ TEST(CallStackProfileMetricsProviderTest, RepeatedStacksUnordered) {
   profile.preserve_sample_ordering = false;
 
   CallStackProfileMetricsProvider provider;
-  provider.SetSourceProfilesForTesting(std::vector<Profile>(1, profile));
+  provider.AppendSourceProfilesForTesting(std::vector<Profile>(1, profile));
   ChromeUserMetricsExtension uma_proto;
   provider.ProvideGeneralMetrics(&uma_proto);
 
@@ -306,7 +333,7 @@ TEST(CallStackProfileMetricsProviderTest, RepeatedStacksUnordered) {
 
 // Checks that only contiguous duplicate samples are collapsed with
 // preserve_sample_ordering = true.
-TEST(CallStackProfileMetricsProviderTest, RepeatedStacksOrdered) {
+TEST_F(CallStackProfileMetricsProviderTest, RepeatedStacksOrdered) {
   const uintptr_t module_base_address = 0x1000;
 
   const Module modules[] = {
@@ -345,7 +372,7 @@ TEST(CallStackProfileMetricsProviderTest, RepeatedStacksOrdered) {
   profile.preserve_sample_ordering = true;
 
   CallStackProfileMetricsProvider provider;
-  provider.SetSourceProfilesForTesting(std::vector<Profile>(1, profile));
+  provider.AppendSourceProfilesForTesting(std::vector<Profile>(1, profile));
   ChromeUserMetricsExtension uma_proto;
   provider.ProvideGeneralMetrics(&uma_proto);
 
@@ -381,9 +408,8 @@ TEST(CallStackProfileMetricsProviderTest, RepeatedStacksOrdered) {
   }
 }
 
-
 // Checks that unknown modules produce an empty Entry.
-TEST(CallStackProfileMetricsProviderTest, UnknownModule) {
+TEST_F(CallStackProfileMetricsProviderTest, UnknownModule) {
   const Frame frame(reinterpret_cast<const void*>(0x1000),
                     Frame::kUnknownModuleIndex);
 
@@ -396,7 +422,7 @@ TEST(CallStackProfileMetricsProviderTest, UnknownModule) {
   profile.preserve_sample_ordering = false;
 
   CallStackProfileMetricsProvider provider;
-  provider.SetSourceProfilesForTesting(std::vector<Profile>(1, profile));
+  provider.AppendSourceProfilesForTesting(std::vector<Profile>(1, profile));
   ChromeUserMetricsExtension uma_proto;
   provider.ProvideGeneralMetrics(&uma_proto);
 
@@ -417,4 +443,32 @@ TEST(CallStackProfileMetricsProviderTest, UnknownModule) {
   EXPECT_FALSE(entry.has_module_id_index());
 }
 
+// Checks that pending profiles are only passed back to ProvideGeneralMetrics
+// once.
+TEST_F(CallStackProfileMetricsProviderTest, ProfilesProvidedOnlyOnce) {
+  CallStackProfileMetricsProvider provider;
+  for (int i = 0; i < 2; ++i) {
+    Profile profile;
+    profile.samples.push_back(Sample(1, Frame(
+        reinterpret_cast<const void*>(0x1000), Frame::kUnknownModuleIndex)));
+
+    profile.profile_duration = base::TimeDelta::FromMilliseconds(100);
+    // Use the sampling period to distinguish the two profiles.
+    profile.sampling_period = base::TimeDelta::FromMilliseconds(i);
+    profile.preserve_sample_ordering = false;
+
+    provider.AppendSourceProfilesForTesting(std::vector<Profile>(1, profile));
+    ChromeUserMetricsExtension uma_proto;
+    provider.ProvideGeneralMetrics(&uma_proto);
+
+    ASSERT_EQ(1, uma_proto.sampled_profile().size());
+    const SampledProfile& sampled_profile = uma_proto.sampled_profile().Get(0);
+    ASSERT_TRUE(sampled_profile.has_call_stack_profile());
+    const CallStackProfile& call_stack_profile =
+        sampled_profile.call_stack_profile();
+    ASSERT_TRUE(call_stack_profile.has_sampling_period_ms());
+    EXPECT_EQ(i, call_stack_profile.sampling_period_ms());
+  }
+}
+
 }  // namespace metrics