Add support for writing system traces at startup

content/browser/tracing/trace_controller_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/tracing/trace_controller_impl.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/strings/string_number_conversions.h"
 #include "content/browser/tracing/trace_message_filter.h"
 #include "content/browser/tracing/trace_subscriber_stdio.h"
 #include "content/common/child_process_messages.h"
 #include "content/public/browser/browser_message_filter.h"
 #include "content/public/common/content_switches.h"
 
+#if defined(OS_CHROMEOS)
+#include "chromeos/dbus/dbus_thread_manager.h"
+#include "chromeos/dbus/debug_daemon_client.h"
+#endif
+
 using base::debug::TraceLog;
 
 namespace content {
 
 namespace {
+#if defined(OS_CHROMEOS)
+const bool kUseSystemTrace = true;
+#else
+const bool kUseSystemTrace = false;
+#endif
+
 
 base::LazyInstance<TraceControllerImpl>::Leaky g_controller =
     LAZY_INSTANCE_INITIALIZER;
 
 class AutoStopTraceSubscriberStdio : public TraceSubscriberStdio {
  public:
   AutoStopTraceSubscriberStdio(const base::FilePath& file_path)
-      : TraceSubscriberStdio(file_path) {}
+      : TraceSubscriberStdio(file_path,
+                             FILE_TYPE_PROPERTY_LIST,
+                             kUseSystemTrace),
+        tracing_completed_(false),
+        system_tracing_completed_(!kUseSystemTrace) {}
 
-  static void EndStartupTrace(TraceSubscriberStdio* subscriber) {
+  static void EndStartupTrace(AutoStopTraceSubscriberStdio* subscriber) {
     if (!TraceControllerImpl::GetInstance()->EndTracingAsync(subscriber))
       delete subscriber;
+#if defined(OS_CHROMEOS)
+    chromeos::DBusThreadManager::Get()->GetDebugDaemonClient()->
+        RequestStopSystemTracing(
+            base::Bind(&AutoStopTraceSubscriberStdio::OnEndSystemTracing,
+            base::Unretained(subscriber)));
+#endif
     // else, the tracing will end asynchronously in OnEndTracingComplete().
   }
 
   virtual void OnEndTracingComplete() OVERRIDE {
     TraceSubscriberStdio::OnEndTracingComplete();
-    delete this;
+    if (system_tracing_completed_)

[dsinclair, 2013/08/19 20:12:26]

Are both of these methods guaranteed to be called from the same thread? If not,
is there a race condition here?

[DaveMoore, 2013/08/19 22:07:46]

I believe they will both be called on the calling thread.
On 2013/08/19 20:12:26, dsinclair wrote:

+      delete this;
     // TODO(joth): this would be the time to automatically open up

[dsinclair, 2013/08/19 20:12:26]

tracing_completed_ = true;?

[DaveMoore, 2013/08/19 22:07:46]

Done.

     // chrome://tracing/ and load up the trace data collected.
   }
+
+  virtual void OnEndSystemTracing(
+      const scoped_refptr<base::RefCountedString>& events_str_ptr)
+      OVERRIDE {
+    TraceSubscriberStdio::OnEndSystemTracing(events_str_ptr);
+    if (tracing_completed_)
+      delete this;

[dsinclair, 2013/08/19 20:12:26]

system_tracing_completed_ = true?

[DaveMoore, 2013/08/19 22:07:46]

Done.

+  }
+
+ private:
+  bool tracing_completed_;
+  bool system_tracing_completed_;
 };
 
 }  // namespace
 
 TraceController* TraceController::GetInstance() {
   return TraceControllerImpl::GetInstance();
 }
 
 TraceControllerImpl::TraceControllerImpl() :
     subscriber_(NULL),
@@ skipping 345 matching lines @@
     // The last ack represents local trace, so we need to ack it now. Note that
     // this code only executes if there were child processes.
     float bpf = TraceLog::GetInstance()->GetBufferPercentFull();
     BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
         base::Bind(&TraceControllerImpl::OnTraceBufferPercentFullReply,
                    base::Unretained(this), bpf));
   }
 }
 
 }  // namespace content