Re-land issue 750183008 (Parallelize trace messages serialization)

content/browser/tracing/tracing_controller_impl.cc

 // Copyright (c) 2013 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/tracing_controller_impl.h"
 
 #include "base/bind.h"
 #include "base/files/file_util.h"
 #include "base/json/string_escape.h"
 #include "base/macros.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 331 matching lines @@
   }
 #endif  // defined(OS_CHROMEOS) || defined(OS_WIN)
 
   // 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_disable_recording_ack_count_ == 1) {
     // Flush asynchronously now, because we don't have any children to wait for.
     TraceLog::GetInstance()->Flush(
         base::Bind(&TracingControllerImpl::OnLocalTraceDataCollected,
-                   base::Unretained(this)));
+                   base::Unretained(this)),
+        true);
   }
 
   // Notify all child processes.
   for (TraceMessageFilterSet::iterator it = trace_message_filters_.begin();
       it != trace_message_filters_.end(); ++it) {
     it->get()->SendEndTracing();
   }
 }
 
 bool TracingControllerImpl::EnableMonitoring(
@@ skipping 312 matching lines @@
     // The response from the specified message filter has already been received.
     return;
   }
 
   if (--pending_disable_recording_ack_count_ == 1) {
     // All acks from subprocesses have been received. Now flush the local trace.
     // During or after this call, our OnLocalTraceDataCollected will be
     // called with the last of the local trace data.
     TraceLog::GetInstance()->Flush(
         base::Bind(&TracingControllerImpl::OnLocalTraceDataCollected,
-                   base::Unretained(this)));
+                   base::Unretained(this)),
+        true);
     return;
   }
 
   if (pending_disable_recording_ack_count_ != 0)
     return;
 
   // All acks (including from the subprocesses and the local trace) have been
   // received.
   is_recording_ = false;
 
@@ skipping 188 matching lines @@
   is_monitoring_ = is_monitoring;
 #if !defined(OS_ANDROID)
   for (std::set<TracingUI*>::iterator it = tracing_uis_.begin();
        it != tracing_uis_.end(); it++) {
     (*it)->OnMonitoringStateChanged(is_monitoring);
   }
 #endif
 }
 
 }  // namespace content