Adds timestamp to the log messages from Chrome in the webrtc native log.

content/renderer/media/webrtc_logging.cc

Index: content/renderer/media/webrtc_logging.cc
diff --git a/content/renderer/media/webrtc_logging.cc b/content/renderer/media/webrtc_logging.cc
index 2bdc7a33e5a5c5cd8c49c274059119029806b819..29cf5f50c9b1e6c1249e5662702c4f0c9c73d093 100644
--- a/content/renderer/media/webrtc_logging.cc
+++ b/content/renderer/media/webrtc_logging.cc
@@ -4,6 +4,10 @@
 
 #include "content/renderer/media/webrtc_logging.h"
 
+#include <iomanip>
+#include <sstream>
+
+#include "base/time/time.h"
 #include "content/public/renderer/webrtc_log_message_delegate.h"
 #include "third_party/libjingle/overrides/talk/base/logging.h"
 
@@ -11,21 +15,44 @@ namespace content {
 
 // Shall only be set once and never go back to NULL.
 WebRtcLogMessageDelegate* g_webrtc_logging_delegate = NULL;
+uint64 g_started_time_ms_ = 0;
 
 void InitWebRtcLoggingDelegate(WebRtcLogMessageDelegate* delegate) {
   CHECK(!g_webrtc_logging_delegate);
   CHECK(delegate);
 
   g_webrtc_logging_delegate = delegate;
+
+  g_started_time_ms_ = base::Time::Now().ToInternalValue() /
+      base::Time::kMicrosecondsPerMillisecond;
+}
+
+void WebRtcLogMessageWithTimestamp(const std::string& message) {
+  if (g_webrtc_logging_delegate)
+    g_webrtc_logging_delegate->LogMessage(message);
 }
 
 void InitWebRtcLogging() {
-  talk_base::InitDiagnosticLoggingDelegateFunction(WebRtcLogMessage);
+  // Log messages from Libjingle should always have timestamps.
+  talk_base::InitDiagnosticLoggingDelegateFunction(
+      WebRtcLogMessageWithTimestamp);
 }
 
 void WebRtcLogMessage(const std::string& message) {
-  if (g_webrtc_logging_delegate)
-    g_webrtc_logging_delegate->LogMessage(message);
+  // Keep consistent with talk_base::DiagnosticLogMessage::CreateTimestamp.
+  // TODO(grunell): remove the duplicated code and unify the timestamp creation.
+  uint64 now_us = base::Time::Now().ToInternalValue();
+  uint64 interval_ms = now_us / base::Time::kMicrosecondsPerMillisecond -
+      g_started_time_ms_;
+
+  std::ostringstream message_oss;
+  message_oss << "[" << std::setfill('0') << std::setw(3)
+              << (interval_ms / 1000)
+              << ":" << std::setw(3)
+              << (interval_ms % 1000)
+              << std::setfill(' ') << "] " << message;
+
+  WebRtcLogMessageWithTimestamp(message_oss.str());
 }
 
 }  // namespace content