[Tracing Clock Sync] Add TracingAgent interface in Chrome

content/browser/tracing/tracing_controller_impl.cc

Index: content/browser/tracing/tracing_controller_impl.cc
diff --git a/content/browser/tracing/tracing_controller_impl.cc b/content/browser/tracing/tracing_controller_impl.cc
index 13a5333fe5a642659586045f42420e0b4ed51aad..de64f832b36d7de84b00464d8e1924a46229444f 100644
--- a/content/browser/tracing/tracing_controller_impl.cc
+++ b/content/browser/tracing/tracing_controller_impl.cc
@@ -45,7 +45,6 @@ namespace {
 base::LazyInstance<TracingControllerImpl>::Leaky g_controller =
     LAZY_INSTANCE_INITIALIZER;
 
-
 std::string GetNetworkTypeString() {
   switch (net::NetworkChangeNotifier::GetConnectionType()) {
     case net::NetworkChangeNotifier::CONNECTION_ETHERNET:
@@ -145,6 +144,7 @@ TracingControllerImpl::TracingControllerImpl()
       approximate_event_count_(0),
       pending_memory_dump_ack_count_(0),
       failed_memory_dump_count_(0),
+      start_tracing_done_callback_(StartTracingDoneCallback()),
     // Tracing may have been enabled by ContentMainRunner if kTraceStartup
     // is specified in command line.
 #if defined(OS_CHROMEOS) || defined(OS_WIN)
@@ -214,6 +214,7 @@ bool TracingControllerImpl::StartTracing(
   if (!can_start_tracing())
     return false;
   is_tracing_ = true;
+  start_tracing_done_callback_ = callback;
 
 #if defined(OS_ANDROID)
   if (pending_get_categories_done_callback_.is_null())
@@ -222,16 +223,17 @@ bool TracingControllerImpl::StartTracing(
 
   if (trace_config.IsSystraceEnabled()) {
     DCHECK(!is_power_tracing_);
-    is_power_tracing_ = PowerTracingAgent::GetInstance()->StartTracing();
+    is_power_tracing_ = PowerTracingAgent::GetInstance()->
+        StartAgentTracing(trace_config);
 #if defined(OS_CHROMEOS)
     DCHECK(!is_system_tracing_);
     chromeos::DBusThreadManager::Get()->GetDebugDaemonClient()->
-      StartSystemTracing();
+        StartAgentTracing(trace_config);
     is_system_tracing_ = true;
 #elif defined(OS_WIN)
     DCHECK(!is_system_tracing_);
     is_system_tracing_ =
-        EtwSystemEventConsumer::GetInstance()->StartSystemTracing();
+        EtwSystemEventConsumer::GetInstance()->StartAgentTracing(trace_config);
 #endif
   }
 
@@ -239,28 +241,10 @@ bool TracingControllerImpl::StartTracing(
   if (TraceLog::GetInstance()->IsEnabled())
     return true;
 
-  base::Closure on_start_tracing_done_callback =
-      base::Bind(&TracingControllerImpl::OnStartTracingDone,
-                 base::Unretained(this),
-                 trace_config, callback);
-  if (!BrowserThread::PostTask(
-          BrowserThread::FILE, FROM_HERE,
-          base::Bind(&TracingControllerImpl::SetEnabledOnFileThread,
-                     base::Unretained(this), trace_config,
-                     base::trace_event::TraceLog::RECORDING_MODE,
-                     on_start_tracing_done_callback))) {
-    // BrowserThread::PostTask fails if the threads haven't been created yet,
-    // so it should be safe to just use TraceLog::SetEnabled directly.
-    base::trace_event::TraceLog::GetInstance()->SetEnabled(
-        trace_config, base::trace_event::TraceLog::RECORDING_MODE);
-    BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
-                            on_start_tracing_done_callback);
-  }
-
-  return true;
+  return StartAgentTracing(trace_config);
 }
 
-void TracingControllerImpl::OnStartTracingDone(
+void TracingControllerImpl::OnStartAgentTracingDone(
     const TraceConfig& trace_config,
     const StartTracingDoneCallback& callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
@@ -326,12 +310,14 @@ void TracingControllerImpl::OnStopTracingDone() {
         BrowserThread::GetBlockingPool();
     chromeos::DBusThreadManager::Get()
         ->GetDebugDaemonClient()
-        ->RequestStopSystemTracing(
-            task_runner,
+        ->SetStopAgentTracingTaskRunner(task_runner);
+    chromeos::DBusThreadManager::Get()
+        ->GetDebugDaemonClient()
+        ->StopAgentTracing(
             base::Bind(&TracingControllerImpl::OnEndSystemTracingAcked,
                        base::Unretained(this)));
 #elif defined(OS_WIN)
-    EtwSystemEventConsumer::GetInstance()->StopSystemTracing(
+    EtwSystemEventConsumer::GetInstance()->StopAgentTracing(
         base::Bind(&TracingControllerImpl::OnEndSystemTracingAcked,
                    base::Unretained(this)));
 #endif
@@ -341,37 +327,12 @@ void TracingControllerImpl::OnStopTracingDone() {
   if (is_power_tracing_) {
     is_power_tracing_ = false;
     ++pending_stop_tracing_ack_count_;
-    PowerTracingAgent::GetInstance()->StopTracing(
+    PowerTracingAgent::GetInstance()->StopAgentTracing(
         base::Bind(&TracingControllerImpl::OnEndPowerTracingAcked,
                    base::Unretained(this)));
   }
 
-  // Handle special case of zero child processes by immediately flushing the
-  // trace log. Once the flush has completed the caller will be notified that
-  // tracing has ended.
-  if (pending_stop_tracing_ack_count_ == 1) {
-    // Flush/cancel asynchronously now, because we don't have any children to
-    // wait for.
-    if (trace_data_sink_) {
-      TraceLog::GetInstance()->Flush(
-          base::Bind(&TracingControllerImpl::OnLocalTraceDataCollected,
-                     base::Unretained(this)),
-          true);
-    } else {
-      TraceLog::GetInstance()->CancelTracing(
-          base::Bind(&TracingControllerImpl::OnLocalTraceDataCollected,
-                     base::Unretained(this)));
-    }
-  }
-
-  // Notify all child processes.
-  for (TraceMessageFilterSet::iterator it = trace_message_filters_.begin();
-      it != trace_message_filters_.end(); ++it) {
-    if (trace_data_sink_)
-      it->get()->SendEndTracing();
-    else
-      it->get()->SendCancelTracing();
-  }
+  StopAgentTracing(StopAgentTracingCallback());
 }
 
 bool TracingControllerImpl::StartMonitoring(
@@ -914,6 +875,82 @@ void TracingControllerImpl::UnregisterTracingUI(TracingUI* tracing_ui) {
   tracing_uis_.erase(it);
 }
 
+std::string TracingControllerImpl::GetTracingAgentName() {
+  return kChromeTracingAgentName;
+}
+
+bool TracingControllerImpl::StartAgentTracing(
+    const base::trace_event::TraceConfig& trace_config) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
+  base::Closure on_start_tracing_done_callback =
+      base::Bind(&TracingControllerImpl::OnStartAgentTracingDone,
+                 base::Unretained(this),
+                 trace_config, start_tracing_done_callback_);
+  if (!BrowserThread::PostTask(
+          BrowserThread::FILE, FROM_HERE,
+          base::Bind(&TracingControllerImpl::SetEnabledOnFileThread,
+                     base::Unretained(this), trace_config,
+                     base::trace_event::TraceLog::RECORDING_MODE,
+                     on_start_tracing_done_callback))) {
+    // BrowserThread::PostTask fails if the threads haven't been created yet,
+    // so it should be safe to just use TraceLog::SetEnabled directly.
+    base::trace_event::TraceLog::GetInstance()->SetEnabled(
+        trace_config, base::trace_event::TraceLog::RECORDING_MODE);
+    BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
+                            on_start_tracing_done_callback);
+  }
+
+  return true;
+}
+
+void TracingControllerImpl::StopAgentTracing(
+    const StopAgentTracingCallback& callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  // Handle special case of zero child processes by immediately flushing the
+  // trace log. Once the flush has completed the caller will be notified that
+  // tracing has ended.
+  if (pending_stop_tracing_ack_count_ == 1) {
+    // Flush/cancel asynchronously now, because we don't have any children to
+    // wait for.
+    if (trace_data_sink_) {
+      TraceLog::GetInstance()->Flush(
+          base::Bind(&TracingControllerImpl::OnLocalTraceDataCollected,
+                     base::Unretained(this)),
+          true);
+    } else {
+      TraceLog::GetInstance()->CancelTracing(
+          base::Bind(&TracingControllerImpl::OnLocalTraceDataCollected,
+                     base::Unretained(this)));
+    }
+  }
+
+  // Notify all child processes.
+  for (TraceMessageFilterSet::iterator it = trace_message_filters_.begin();
+      it != trace_message_filters_.end(); ++it) {
+    if (trace_data_sink_)
+      it->get()->SendEndTracing();
+    else
+      it->get()->SendCancelTracing();
+  }
+}
+
+bool TracingControllerImpl::SupportsExplicitClockSync() {
+  // TODO(zhenw): return true after implementing explicit clock sync.
+  return false;
+}
+
+void TracingControllerImpl::RecordClockSyncMarker(
+    scoped_ptr<base::DictionaryValue> marker) {
+  DCHECK(SupportsExplicitClockSync());
+  // TODO(zhenw): implement explicit clock sync.
+}
+
+void TracingControllerImpl::IssueClockSyncMarker() {
+  DCHECK(SupportsExplicitClockSync());
+  // TODO(zhenw): implement explicit clock sync.
+}
+
 void TracingControllerImpl::RequestGlobalMemoryDump(
     const base::trace_event::MemoryDumpRequestArgs& args,
     const base::trace_event::MemoryDumpCallback& callback) {