Enable startup profiling by Win x64 stack sampling profiler

components/metrics/call_stack_profile_metrics_provider.cc

Index: components/metrics/call_stack_profile_metrics_provider.cc
diff --git a/components/metrics/call_stack_profile_metrics_provider.cc b/components/metrics/call_stack_profile_metrics_provider.cc
index f96923bc5193d350be9fd8c96f922ab4cb725043..674af70afab108aa83ab2755caacd31fd28077c4 100644
--- a/components/metrics/call_stack_profile_metrics_provider.cc
+++ b/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