Change g_webrtc_logging_delegate from process-level to RenderThread-level

content/renderer/media/webrtc_logging.cc

 // Copyright 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/renderer/media/webrtc_logging.h"
 
 #include "base/time/time.h"
+#include "base/lazy_instance.h"
+#include "base/threading/thread_local.h"
 #include "content/public/renderer/webrtc_log_message_delegate.h"
 #include "third_party/webrtc/overrides/webrtc/base/logging.h"
 
 namespace content {
 
-// Shall only be set once and never go back to NULL.
-WebRtcLogMessageDelegate* g_webrtc_logging_delegate = NULL;
+// Shall only be set once within a RenderThread and never go back to NULL.
+base::LazyInstance<base::ThreadLocalPointer<WebRtcLogMessageDelegate> >::Leaky
+    g_webrtc_logging_delegate_tls = LAZY_INSTANCE_INITIALIZER;
 
 void InitWebRtcLoggingDelegate(WebRtcLogMessageDelegate* delegate) {
-  CHECK(!g_webrtc_logging_delegate);
+  CHECK(!g_webrtc_logging_delegate_tls.Pointer()->Get());
   CHECK(delegate);
 
-  g_webrtc_logging_delegate = delegate;
+  g_webrtc_logging_delegate_tls.Pointer()->Set(delegate);
 }
 
 void InitWebRtcLogging() {
   // Log messages from Libjingle should not have timestamps.
   rtc::InitDiagnosticLoggingDelegateFunction(&WebRtcLogMessage);
 }
 
 void WebRtcLogMessage(const std::string& message) {
-  if (g_webrtc_logging_delegate)
-    g_webrtc_logging_delegate->LogMessage(message);
+  if (g_webrtc_logging_delegate_tls.Pointer()->Get())
+    g_webrtc_logging_delegate_tls.Pointer()->Get()->LogMessage(message);
 }
 
 }  // namespace content