Implement browser-side logging to WebRtc log

This adds a logging callback to RenderProcessHost and also adds logging
for device enumeration in the browser process.

BUG=332261

Review URL: https://codereview.chromium.org/140843007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247164 0039d316-1c4b-4281-b951-d872f2087c98

30 files changed, 222 insertions, 41 deletions

diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index 94a6ae7..5a671a2 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -921,6 +921,8 @@ void ChromeContentBrowserClient::RenderProcessWillLaunch(
 #if defined(ENABLE_WEBRTC)
   WebRtcLoggingHandlerHost* webrtc_logging_handler_host =
       new WebRtcLoggingHandlerHost(profile);
+  host->SetWebRtcLogMessageCallback(base::Bind(
+      &WebRtcLoggingHandlerHost::LogMessage, webrtc_logging_handler_host));
   host->AddFilter(webrtc_logging_handler_host);
   host->SetUserData(host, new base::UserDataAdapter<WebRtcLoggingHandlerHost>(
       webrtc_logging_handler_host));
diff --git a/chrome/browser/media/webrtc_logging_handler_host.cc b/chrome/browser/media/webrtc_logging_handler_host.cc
index 611bc52..31759bb 100644
--- a/chrome/browser/media/webrtc_logging_handler_host.cc
+++ b/chrome/browser/media/webrtc_logging_handler_host.cc
@@ -203,6 +203,14 @@ void WebRtcLoggingHandlerHost::DiscardLog(const GenericDoneCallback& callback) {
   FireGenericDoneCallback(&discard_callback, true, "");
 }
 
+void WebRtcLoggingHandlerHost::LogMessage(const std::string& message) {
+  BrowserThread::PostTask(
+      BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(
+          &WebRtcLoggingHandlerHost::AddLogMessageFromBrowser, this, message));
+}
+
 void WebRtcLoggingHandlerHost::OnChannelClosing() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   if (logging_state_ == STARTED || logging_state_ == STOPPED) {
@@ -234,6 +242,13 @@ bool WebRtcLoggingHandlerHost::OnMessageReceived(const IPC::Message& message,
   return handled;
 }
 
+void WebRtcLoggingHandlerHost::AddLogMessageFromBrowser(
+    const std::string& message) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  if (logging_state_ == STARTED)
+    LogToCircularBuffer(message);
+}
+
 void WebRtcLoggingHandlerHost::OnAddLogMessage(const std::string& message) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   if (logging_state_ == STARTED || logging_state_ == STOPPING)
diff --git a/chrome/browser/media/webrtc_logging_handler_host.h b/chrome/browser/media/webrtc_logging_handler_host.h
index 5f7f5a4..3ce35cb 100644
--- a/chrome/browser/media/webrtc_logging_handler_host.h
+++ b/chrome/browser/media/webrtc_logging_handler_host.h
@@ -61,6 +61,9 @@ class WebRtcLoggingHandlerHost : public content::BrowserMessageFilter {
   // called on the IO thread.
   void DiscardLog(const GenericDoneCallback& callback);
 
+  // Adds a message to the log.
+  void LogMessage(const std::string& message);
+
   // May be called on any thread. |upload_log_on_render_close_| is used
   // for decision making and it's OK if it changes before the execution based
   // on that decision has finished.
@@ -99,9 +102,13 @@ class WebRtcLoggingHandlerHost : public content::BrowserMessageFilter {
   virtual bool OnMessageReceived(const IPC::Message& message,
                                  bool* message_was_ok) OVERRIDE;
 
+  // Handles log message requests from both renderer process.
   void OnAddLogMessage(const std::string& message);
   void OnLoggingStoppedInRenderer();
 
+  // Handles log message requests from browser process.
+  void AddLogMessageFromBrowser(const std::string& message);
+
   void StartLoggingIfAllowed();
   void DoStartLogging();
   void LogMachineInfo();
diff --git a/content/browser/renderer_host/media/audio_input_renderer_host.cc b/content/browser/renderer_host/media/audio_input_renderer_host.cc
index ec61944..93ed16c 100644
--- a/content/browser/renderer_host/media/audio_input_renderer_host.cc
+++ b/content/browser/renderer_host/media/audio_input_renderer_host.cc
@@ -176,6 +176,8 @@ void AudioInputRendererHost::DoSendRecordingMessage(
 void AudioInputRendererHost::DoHandleError(
     media::AudioInputController* controller) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  MediaStreamManager::SendMessageToNativeLog(
+      "The AudioInputController signalled an error.");
 
   AudioEntry* entry = LookupByController(controller);
   if (!entry)
@@ -310,6 +312,8 @@ void AudioInputRendererHost::OnCreateStream(
   entry->stream_id = stream_id;
   audio_entries_.insert(std::make_pair(stream_id, entry.release()));
 
+  MediaStreamManager::SendMessageToNativeLog(
+      "Audio input stream created successfully.");
   audio_log_->OnCreated(stream_id, audio_params, device_id, std::string());
 }
 
@@ -349,6 +353,8 @@ void AudioInputRendererHost::OnSetVolume(int stream_id, double volume) {
 }
 
 void AudioInputRendererHost::SendErrorMessage(int stream_id) {
+  MediaStreamManager::SendMessageToNativeLog(
+      "An error occurred in AudioInputRendererHost.");
   Send(new AudioInputMsg_NotifyStreamStateChanged(
       stream_id, media::AudioInputIPCDelegate::kError));
 }
diff --git a/content/browser/renderer_host/media/desktop_capture_device.cc b/content/browser/renderer_host/media/desktop_capture_device.cc
index d09131b..7c78df0 100644
--- a/content/browser/renderer_host/media/desktop_capture_device.cc
+++ b/content/browser/renderer_host/media/desktop_capture_device.cc
@@ -165,8 +165,9 @@ void DesktopCaptureDevice::Core::OnCaptureCompleted(
   capture_in_progress_ = false;
 
   if (!frame) {
-    LOG(ERROR) << "Failed to capture a frame.";
-    client_->OnError();
+    std::string log("Failed to capture a frame.");
+    LOG(ERROR) << log;
+    client_->OnError(log);
     return;
   }
 
diff --git a/content/browser/renderer_host/media/desktop_capture_device_aura.cc b/content/browser/renderer_host/media/desktop_capture_device_aura.cc
index 03e9c89..7d9e7d9 100644
--- a/content/browser/renderer_host/media/desktop_capture_device_aura.cc
+++ b/content/browser/renderer_host/media/desktop_capture_device_aura.cc
@@ -405,7 +405,7 @@ void DesktopVideoCaptureMachine::OnWindowDestroyed(aura::Window* window) {
 
   Stop(base::Bind(&base::DoNothing));
 
-  oracle_proxy_->ReportError();
+  oracle_proxy_->ReportError("OnWindowDestroyed()");
 }
 
 void DesktopVideoCaptureMachine::OnCompositingEnded(
diff --git a/content/browser/renderer_host/media/desktop_capture_device_aura_unittest.cc b/content/browser/renderer_host/media/desktop_capture_device_aura_unittest.cc
index 2dd75f7..e6abac3 100644
--- a/content/browser/renderer_host/media/desktop_capture_device_aura_unittest.cc
+++ b/content/browser/renderer_host/media/desktop_capture_device_aura_unittest.cc
@@ -32,7 +32,7 @@ class MockDeviceClient : public media::VideoCaptureDevice::Client {
   MOCK_METHOD2(ReserveOutputBuffer,
                scoped_refptr<Buffer>(media::VideoFrame::Format format,
                                      const gfx::Size& dimensions));
-  MOCK_METHOD0(OnError, void());
+  MOCK_METHOD1(OnError, void(const std::string& reason));
   MOCK_METHOD5(OnIncomingCapturedFrame,
                void(const uint8* data,
                     int length,
@@ -99,7 +99,7 @@ TEST_F(DesktopCaptureDeviceAuraTest, StartAndStop) {
           content::DesktopMediaID::RegisterAuraWindow(root_window())));
 
   scoped_ptr<MockDeviceClient> client(new MockDeviceClient());
-  EXPECT_CALL(*client, OnError()).Times(0);
+  EXPECT_CALL(*client, OnError(_)).Times(0);
 
   media::VideoCaptureParams capture_params;
   capture_params.requested_format.frame_size.SetSize(640, 480);
diff --git a/content/browser/renderer_host/media/desktop_capture_device_unittest.cc b/content/browser/renderer_host/media/desktop_capture_device_unittest.cc
index 90ac57b..c51172a 100644
--- a/content/browser/renderer_host/media/desktop_capture_device_unittest.cc
+++ b/content/browser/renderer_host/media/desktop_capture_device_unittest.cc
@@ -43,7 +43,7 @@ class MockDeviceClient : public media::VideoCaptureDevice::Client {
   MOCK_METHOD2(ReserveOutputBuffer,
                scoped_refptr<Buffer>(media::VideoFrame::Format format,
                                      const gfx::Size& dimensions));
-  MOCK_METHOD0(OnError, void());
+  MOCK_METHOD1(OnError, void(const std::string& reason));
   MOCK_METHOD5(OnIncomingCapturedFrame,
                void(const uint8* data,
                     int length,
@@ -164,7 +164,7 @@ TEST_F(DesktopCaptureDeviceTest, MAYBE_Capture) {
   int frame_size;
 
   scoped_ptr<MockDeviceClient> client(new MockDeviceClient());
-  EXPECT_CALL(*client, OnError()).Times(0);
+  EXPECT_CALL(*client, OnError(_)).Times(0);
   EXPECT_CALL(*client, OnIncomingCapturedFrame(_, _, _, _, _))
       .WillRepeatedly(
            DoAll(SaveArg<1>(&frame_size),
@@ -204,7 +204,7 @@ TEST_F(DesktopCaptureDeviceTest, ScreenResolutionChangeConstantResolution) {
   int frame_size;
 
   scoped_ptr<MockDeviceClient> client(new MockDeviceClient());
-  EXPECT_CALL(*client, OnError()).Times(0);
+  EXPECT_CALL(*client, OnError(_)).Times(0);
   EXPECT_CALL(*client, OnIncomingCapturedFrame(_, _, _, _, _))
       .WillRepeatedly(
            DoAll(SaveArg<1>(&frame_size),
@@ -251,7 +251,7 @@ TEST_F(DesktopCaptureDeviceTest, ScreenResolutionChangeVariableResolution) {
   base::WaitableEvent done_event(false, false);
 
   scoped_ptr<MockDeviceClient> client(new MockDeviceClient());
-  EXPECT_CALL(*client, OnError()).Times(0);
+  EXPECT_CALL(*client, OnError(_)).Times(0);
   EXPECT_CALL(*client, OnIncomingCapturedFrame(_, _, _, _, _))
       .WillRepeatedly(
            DoAll(SaveArg<4>(&format),
diff --git a/content/browser/renderer_host/media/media_stream_manager.cc b/content/browser/renderer_host/media/media_stream_manager.cc
index 6ed73ca..6832d62 100644
--- a/content/browser/renderer_host/media/media_stream_manager.cc
+++ b/content/browser/renderer_host/media/media_stream_manager.cc
@@ -13,18 +13,22 @@
 #include "base/logging.h"
 #include "base/rand_util.h"
 #include "base/run_loop.h"
+#include "base/strings/stringprintf.h"
 #include "base/threading/thread.h"
+#include "content/browser/browser_main_loop.h"
 #include "content/browser/renderer_host/media/audio_input_device_manager.h"
 #include "content/browser/renderer_host/media/device_request_message_filter.h"
 #include "content/browser/renderer_host/media/media_stream_requester.h"
 #include "content/browser/renderer_host/media/media_stream_ui_proxy.h"
 #include "content/browser/renderer_host/media/video_capture_manager.h"
 #include "content/browser/renderer_host/media/web_contents_capture_util.h"
+#include "content/browser/renderer_host/render_process_host_impl.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/content_browser_client.h"
 #include "content/public/browser/media_device_id.h"
 #include "content/public/browser/media_observer.h"
 #include "content/public/browser/media_request_state.h"
+#include "content/public/browser/render_process_host.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/common/media_stream_request.h"
 #include "media/audio/audio_manager_base.h"
@@ -103,6 +107,39 @@ void ParseStreamType(const StreamOptions& options,
   }
 }
 
+// Private helper method for SendMessageToNativeLog() that obtains the global
+// MediaStreamManager instance on the UI thread before sending |message| to the
+// webrtcLoggingPrivate API.
+void DoAddLogMessage(const std::string& message) {
+  // Must be on the UI thread to access BrowserMainLoop.
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  // May be null in tests.
+  // TODO(vrk): Handle this more elegantly by having native log messages become
+  // no-ops until MediaStreamManager is aware that a renderer process has
+  // started logging. crbug.com/333894
+  if (content::BrowserMainLoop::GetInstance()) {
+    content::BrowserMainLoop::GetInstance()->
+        media_stream_manager()->AddLogMessageOnUIThread(message);
+  }
+}
+
+// Private helper method to generate a string for the log message that lists the
+// human readable names of |devices|.
+std::string GetLogMessageString(MediaStreamType stream_type,
+                                const StreamDeviceInfoArray& devices) {
+  std::string output_string =
+      base::StringPrintf("Getting devices for stream type %d:\n", stream_type);
+  if (devices.empty()) {
+    output_string += "No devices found.";
+  } else {
+    for (StreamDeviceInfoArray::const_iterator it = devices.begin();
+         it != devices.end(); ++it) {
+      output_string += "  " + it->device.name + "\n";
+    }
+  }
+  return output_string;
+}
+
 }  // namespace
 
 
@@ -1014,6 +1051,20 @@ void MediaStreamManager::SetupRequest(const std::string& label) {
       // Enumerate the devices if there is no valid device lists to be used.
       StartEnumeration(request);
       return;
+    } else {
+        // Cache is valid, so log the cached devices for MediaStream requests.
+      if (request->request_type == MEDIA_GENERATE_STREAM) {
+        std::string log_message("Using cached devices for request.\n");
+        if (audio_type != MEDIA_NO_SERVICE) {
+          log_message +=
+              GetLogMessageString(audio_type, audio_enumeration_cache_.devices);
+        }
+        if (video_type != MEDIA_NO_SERVICE) {
+          log_message +=
+              GetLogMessageString(video_type, video_enumeration_cache_.devices);
+        }
+        SendMessageToNativeLog(log_message);
+      }
     }
 
     if (!SetupDeviceCaptureRequest(request)) {
@@ -1403,7 +1454,11 @@ void MediaStreamManager::DevicesEnumerated(
     MediaStreamType stream_type, const StreamDeviceInfoArray& devices) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   DVLOG(1) << "DevicesEnumerated("
-           << ", {stream_type = " << stream_type <<  "})";
+           << "{stream_type = " << stream_type << "})" << std::endl;
+
+  std::string log_message = "New device enumeration result:\n" +
+                            GetLogMessageString(stream_type, devices);
+  SendMessageToNativeLog(log_message);
 
   // Only cache the device list when the device list has been changed.
   bool need_update_clients = false;
@@ -1476,6 +1531,47 @@ void MediaStreamManager::DevicesEnumerated(
   DCHECK_GE(active_enumeration_ref_count_[stream_type], 0);
 }
 
+// static
+void MediaStreamManager::SendMessageToNativeLog(const std::string& message) {
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      base::Bind(DoAddLogMessage, message));
+}
+
+void MediaStreamManager::AddLogMessageOnUIThread(const std::string& message) {
+#if defined(OS_ANDROID)
+  // It appears android_aosp is being built with ENABLE_WEBRTC=0, since it does
+  // not find RenderProcessHostImpl::WebRtcLogMessage. Logging is not enabled on
+  // Android anyway, so make this function a no-op.
+  // TODO(vrk): Figure out what's going on here and fix.
+  return;
+#else
+  // Must be on the UI thread to access RenderProcessHost from process ID.
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  // Grab all unique process ids that request a MediaStream or have a
+  // MediaStream running.
+  std::set<int> requesting_process_ids;
+  for (DeviceRequests::const_iterator it = requests_.begin();
+       it != requests_.end(); ++it) {
+    DeviceRequest* request = it->second;
+    if (request->request_type == MEDIA_GENERATE_STREAM)
+      requesting_process_ids.insert(request->requesting_process_id);
+  }
+
+  for (std::set<int>::const_iterator it = requesting_process_ids.begin();
+       it != requesting_process_ids.end(); ++it) {
+    // Log the message to all renderers that are requesting a MediaStream or
+    // have a MediaStream running.
+    content::RenderProcessHostImpl* render_process_host_impl =
+        static_cast<content::RenderProcessHostImpl*>(
+            content::RenderProcessHost::FromID(*it));
+    if (render_process_host_impl)
+      render_process_host_impl->WebRtcLogMessage(message);
+  }
+#endif
+}
+
 void MediaStreamManager::HandleAccessRequestResponse(
     const std::string& label,
     const MediaStreamDevices& devices) {
diff --git a/content/browser/renderer_host/media/media_stream_manager.h b/content/browser/renderer_host/media/media_stream_manager.h
index eefab6b..8c2edc4 100644
--- a/content/browser/renderer_host/media/media_stream_manager.h
+++ b/content/browser/renderer_host/media/media_stream_manager.h
@@ -185,6 +185,15 @@ class CONTENT_EXPORT MediaStreamManager
   // too late. (see http://crbug.com/247525#c14).
   virtual void WillDestroyCurrentMessageLoop() OVERRIDE;
 
+  // Sends log messages to the render processes making device requests, to be
+  // used by the webrtcLoggingPrivate API if requested.
+  void AddLogMessageOnUIThread(const std::string& message);
+
+  // Adds |message| to native logs for outstanding device requests, for use by
+  // render processes requesting logging from webrtcLoggingPrivate API. Safe to
+  // call from any thread.
+  static void SendMessageToNativeLog(const std::string& message);
+
  protected:
   // Used for testing.
   MediaStreamManager();
diff --git a/content/browser/renderer_host/media/video_capture_controller.cc b/content/browser/renderer_host/media/video_capture_controller.cc
index f23f50f..5dff5c2 100644
--- a/content/browser/renderer_host/media/video_capture_controller.cc
+++ b/content/browser/renderer_host/media/video_capture_controller.cc
@@ -121,7 +121,7 @@ class VideoCaptureController::VideoCaptureDeviceClient
                                         const gfx::Size& dimensions,
                                         base::TimeTicks timestamp,
                                         int frame_rate) OVERRIDE;
-  virtual void OnError() OVERRIDE;
+  virtual void OnError(const std::string& reason) OVERRIDE;
 
  private:
   scoped_refptr<Buffer> DoReserveOutputBuffer(media::VideoFrame::Format format,
@@ -428,7 +428,10 @@ void VideoCaptureController::VideoCaptureDeviceClient::OnIncomingCapturedBuffer(
           timestamp));
 }
 
-void VideoCaptureController::VideoCaptureDeviceClient::OnError() {
+void VideoCaptureController::VideoCaptureDeviceClient::OnError(
+    const std::string& reason) {
+  MediaStreamManager::SendMessageToNativeLog(
+      "Error on video capture: " + reason);
   BrowserThread::PostTask(BrowserThread::IO,
       FROM_HERE,
       base::Bind(&VideoCaptureController::DoErrorOnIOThread, controller_));
diff --git a/content/browser/renderer_host/media/video_capture_controller_unittest.cc b/content/browser/renderer_host/media/video_capture_controller_unittest.cc
index 1852a71..b4de263 100644
--- a/content/browser/renderer_host/media/video_capture_controller_unittest.cc
+++ b/content/browser/renderer_host/media/video_capture_controller_unittest.cc
@@ -407,7 +407,7 @@ TEST_F(VideoCaptureControllerTest, ErrorBeforeDeviceCreation) {
   // Start with one client.
   controller_->AddClient(
       route_id, client_a_.get(), base::kNullProcessHandle, 100, session_100);
-  device_->OnError();
+  device_->OnError("Test Error");
   EXPECT_CALL(*client_a_, DoError(route_id)).Times(1);
   base::RunLoop().RunUntilIdle();
   Mock::VerifyAndClearExpectations(client_a_.get());
@@ -462,7 +462,7 @@ TEST_F(VideoCaptureControllerTest, ErrorAfterDeviceCreation) {
       device_->ReserveOutputBuffer(media::VideoFrame::I420, dims);
   ASSERT_TRUE(buffer);
 
-  device_->OnError();
+  device_->OnError("Test error");
   device_->OnIncomingCapturedBuffer(buffer,
                                     media::VideoFrame::I420,
                                     dims,
diff --git a/content/browser/renderer_host/media/video_capture_device_impl.cc b/content/browser/renderer_host/media/video_capture_device_impl.cc
index 045eda6..88e5ab5 100644
--- a/content/browser/renderer_host/media/video_capture_device_impl.cc
+++ b/content/browser/renderer_host/media/video_capture_device_impl.cc
@@ -155,10 +155,10 @@ void ThreadSafeCaptureOracle::Stop() {
   client_.reset();
 }
 
-void ThreadSafeCaptureOracle::ReportError() {
+void ThreadSafeCaptureOracle::ReportError(const std::string& reason) {
   base::AutoLock guard(lock_);
   if (client_)
-    client_->OnError();
+    client_->OnError(reason);
 }
 
 void ThreadSafeCaptureOracle::DidCaptureFrame(
@@ -196,16 +196,19 @@ void VideoCaptureDeviceImpl::AllocateAndStart(
   }
 
   if (params.requested_format.frame_rate <= 0) {
-    DVLOG(1) << "invalid frame_rate: " << params.requested_format.frame_rate;
-    client->OnError();
+    std::string error_msg = base::StringPrintf(
+        "invalid frame_rate: %d", params.requested_format.frame_rate);
+    DVLOG(1) << error_msg;
+    client->OnError(error_msg);
     return;
   }
 
   if (params.requested_format.frame_size.width() < kMinFrameWidth ||
       params.requested_format.frame_size.height() < kMinFrameHeight) {
-    DVLOG(1) << "invalid frame size: "
-             << params.requested_format.frame_size.ToString();
-    client->OnError();
+    std::string error_msg =
+        "invalid frame size: " + params.requested_format.frame_size.ToString();
+    DVLOG(1) << error_msg;
+    client->OnError(error_msg);
     return;
   }
 
@@ -252,8 +255,9 @@ void VideoCaptureDeviceImpl::StopAndDeAllocate() {
 void VideoCaptureDeviceImpl::CaptureStarted(bool success) {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (!success) {
-    DVLOG(1) << "Failed to start capture machine.";
-    Error();
+    std::string reason("Failed to start capture machine.");
+    DVLOG(1) << reason;
+    Error(reason);
   }
 }
 
@@ -291,14 +295,14 @@ void VideoCaptureDeviceImpl::TransitionStateTo(State next_state) {
   state_ = next_state;
 }
 
-void VideoCaptureDeviceImpl::Error() {
+void VideoCaptureDeviceImpl::Error(const std::string& reason) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   if (state_ == kIdle)
     return;
 
   if (oracle_proxy_)
-    oracle_proxy_->ReportError();
+    oracle_proxy_->ReportError(reason);
 
   StopAndDeAllocate();
   TransitionStateTo(kError);
diff --git a/content/browser/renderer_host/media/video_capture_device_impl.h b/content/browser/renderer_host/media/video_capture_device_impl.h
index 56bf1e0..87d4c19 100644
--- a/content/browser/renderer_host/media/video_capture_device_impl.h
+++ b/content/browser/renderer_host/media/video_capture_device_impl.h
@@ -71,7 +71,7 @@ class ThreadSafeCaptureOracle
   void Stop();
 
   // Signal an error to the client.
-  void ReportError();
+  void ReportError(const std::string& reason);
 
  private:
   friend class base::RefCountedThreadSafe<ThreadSafeCaptureOracle>;
@@ -165,7 +165,7 @@ class CONTENT_EXPORT VideoCaptureDeviceImpl
   void CaptureStarted(bool success);
 
   // Stops capturing and notifies client_ of an error state.
-  void Error();
+  void Error(const std::string& reason);
 
   // Tracks that all activity occurs on the media stream manager's thread.
   base::ThreadChecker thread_checker_;
diff --git a/content/browser/renderer_host/media/video_capture_manager.cc b/content/browser/renderer_host/media/video_capture_manager.cc
index ace6565..28242f4 100644
--- a/content/browser/renderer_host/media/video_capture_manager.cc
+++ b/content/browser/renderer_host/media/video_capture_manager.cc
@@ -213,7 +213,7 @@ void VideoCaptureManager::DoStartDeviceOnDeviceThread(
   }
 
   if (!video_capture_device) {
-    device_client->OnError();
+    device_client->OnError("Could not create capture device");
     return;
   }
 
diff --git a/content/browser/renderer_host/media/web_contents_video_capture_device.cc b/content/browser/renderer_host/media/web_contents_video_capture_device.cc
index 535111b..95333fc 100644
--- a/content/browser/renderer_host/media/web_contents_video_capture_device.cc
+++ b/content/browser/renderer_host/media/web_contents_video_capture_device.cc
@@ -700,7 +700,7 @@ void WebContentsCaptureMachine::WebContentsDestroyed(
 
   subscription_.reset();
   web_contents->DecrementCapturerCount();
-  oracle_proxy_->ReportError();
+  oracle_proxy_->ReportError("WebContentsDestroyed()");
 }
 
 RenderWidgetHost* WebContentsCaptureMachine::GetTarget() {
diff --git a/content/browser/renderer_host/media/web_contents_video_capture_device_unittest.cc b/content/browser/renderer_host/media/web_contents_video_capture_device_unittest.cc
index 39b427b..5787d2b 100644
--- a/content/browser/renderer_host/media/web_contents_video_capture_device_unittest.cc
+++ b/content/browser/renderer_host/media/web_contents_video_capture_device_unittest.cc
@@ -361,7 +361,7 @@ class StubClient : public media::VideoCaptureDevice::Client {
     color_callback_.Run((SkColorSetRGB(yuv[0], yuv[1], yuv[2])));
   }
 
-  virtual void OnError() OVERRIDE {
+  virtual void OnError(const std::string& reason) OVERRIDE {
     error_callback_.Run();
   }
 
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index 14c0cd2..60881ea 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -1516,6 +1516,11 @@ void RenderProcessHostImpl::DisableAecDump() {
       base::Bind(&RenderProcessHostImpl::SendDisableAecDumpToRenderer,
                  weak_factory_.GetWeakPtr()));
 }
+
+void RenderProcessHostImpl::SetWebRtcLogMessageCallback(
+    base::Callback<void(const std::string&)> callback) {
+  webrtc_log_message_callback_ = callback;
+}
 #endif
 
 IPC::ChannelProxy* RenderProcessHostImpl::GetChannel() {
@@ -1882,6 +1887,14 @@ void RenderProcessHostImpl::EndFrameSubscription(int route_id) {
       route_id));
 }
 
+#if defined(ENABLE_WEBRTC)
+void RenderProcessHostImpl::WebRtcLogMessage(const std::string& message) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  if (!webrtc_log_message_callback_.is_null())
+    webrtc_log_message_callback_.Run(message);
+}
+#endif
+
 void RenderProcessHostImpl::OnShutdownRequest() {
   // Don't shut down if there are active RenderViews, or if there are pending
   // RenderViews being swapped back in.
diff --git a/content/browser/renderer_host/render_process_host_impl.h b/content/browser/renderer_host/render_process_host_impl.h
index 73522cb..a2d8df5 100644
--- a/content/browser/renderer_host/render_process_host_impl.h
+++ b/content/browser/renderer_host/render_process_host_impl.h
@@ -124,6 +124,8 @@ class CONTENT_EXPORT RenderProcessHostImpl
 #if defined(ENABLE_WEBRTC)
   virtual void EnableAecDump(const base::FilePath& file) OVERRIDE;
   virtual void DisableAecDump() OVERRIDE;
+  virtual void SetWebRtcLogMessageCallback(
+      base::Callback<void(const std::string&)> callback) OVERRIDE;
 #endif
 
   // IPC::Sender via RenderProcessHost.
@@ -165,6 +167,11 @@ class CONTENT_EXPORT RenderProcessHostImpl
     return make_scoped_refptr(geolocation_dispatcher_host_);
   }
 
+#if defined(ENABLE_WEBRTC)
+  // Fires the webrtc log message callback with |message|, if callback is set.
+  void WebRtcLogMessage(const std::string& message);
+#endif
+
   // Register/unregister the host identified by the host id in the global host
   // list.
   static void RegisterHost(int host_id, RenderProcessHost* host);
@@ -389,6 +396,10 @@ class CONTENT_EXPORT RenderProcessHostImpl
   // Message filter for geolocation messages.
   GeolocationDispatcherHost* geolocation_dispatcher_host_;
 
+#if defined(ENABLE_WEBRTC)
+  base::Callback<void(const std::string&)> webrtc_log_message_callback_;
+#endif
+
   // Lives on the browser's ChildThread.
   base::WeakPtrFactory<RenderProcessHostImpl> weak_factory_;
 
diff --git a/content/public/browser/render_process_host.h b/content/public/browser/render_process_host.h
index 436108a..faa42eb 100644
--- a/content/public/browser/render_process_host.h
+++ b/content/public/browser/render_process_host.h
@@ -215,6 +215,12 @@ class CONTENT_EXPORT RenderProcessHost : public IPC::Sender,
 #if defined(ENABLE_WEBRTC)
   virtual void EnableAecDump(const base::FilePath& file) = 0;
   virtual void DisableAecDump() = 0;
+
+  // When set, |callback| receives log messages regarding, for example. media
+  // devices (webcams, mics, etc) that were initially requested in the render
+  // process associated with this RenderProcessHost.
+  virtual void SetWebRtcLogMessageCallback(
+      base::Callback<void(const std::string&)> callback) = 0;
 #endif
 
   // Static management functions -----------------------------------------------
diff --git a/content/public/test/mock_render_process_host.cc b/content/public/test/mock_render_process_host.cc
index 1fc3eab..5e67bf8 100644
--- a/content/public/test/mock_render_process_host.cc
+++ b/content/public/test/mock_render_process_host.cc
@@ -257,6 +257,10 @@ void MockRenderProcessHost::EnableAecDump(const base::FilePath& file) {
 
 void MockRenderProcessHost::DisableAecDump() {
 }
+
+void MockRenderProcessHost::SetWebRtcLogMessageCallback(
+    base::Callback<void(const std::string&)> callback) {
+}
 #endif
 
 bool MockRenderProcessHost::OnMessageReceived(const IPC::Message& msg) {
diff --git a/content/public/test/mock_render_process_host.h b/content/public/test/mock_render_process_host.h
index d76fa66..d3c9739 100644
--- a/content/public/test/mock_render_process_host.h
+++ b/content/public/test/mock_render_process_host.h
@@ -78,6 +78,8 @@ class MockRenderProcessHost : public RenderProcessHost {
 #if defined(ENABLE_WEBRTC)
   virtual void EnableAecDump(const base::FilePath& file) OVERRIDE;
   virtual void DisableAecDump() OVERRIDE;
+  virtual void SetWebRtcLogMessageCallback(
+      base::Callback<void(const std::string&)> callback) OVERRIDE;
 #endif
 
   // IPC::Sender via RenderProcessHost.
diff --git a/media/video/capture/android/video_capture_device_android.cc b/media/video/capture/android/video_capture_device_android.cc
index 54ca9de..cbf5005 100644
--- a/media/video/capture/android/video_capture_device_android.cc
+++ b/media/video/capture/android/video_capture_device_android.cc
@@ -259,7 +259,7 @@ void VideoCaptureDeviceAndroid::SetErrorState(const std::string& reason) {
     base::AutoLock lock(lock_);
     state_ = kError;
   }
-  client_->OnError();
+  client_->OnError(reason);
 }
 
 }  // namespace media
diff --git a/media/video/capture/linux/video_capture_device_linux.cc b/media/video/capture/linux/video_capture_device_linux.cc
index a6f85d5..7155ae23 100644
--- a/media/video/capture/linux/video_capture_device_linux.cc
+++ b/media/video/capture/linux/video_capture_device_linux.cc
@@ -607,7 +607,7 @@ void VideoCaptureDeviceLinux::SetErrorState(const std::string& reason) {
          v4l2_thread_.message_loop() == base::MessageLoop::current());
   DVLOG(1) << reason;
   state_ = kError;
-  client_->OnError();
+  client_->OnError(reason);
 }
 
 }  // namespace media
diff --git a/media/video/capture/mac/video_capture_device_mac.mm b/media/video/capture/mac/video_capture_device_mac.mm
index 97e4363..8ff066f 100644
--- a/media/video/capture/mac/video_capture_device_mac.mm
+++ b/media/video/capture/mac/video_capture_device_mac.mm
@@ -322,7 +322,7 @@ void VideoCaptureDeviceMac::SetErrorState(const std::string& reason) {
   DCHECK(task_runner_->BelongsToCurrentThread());
   DLOG(ERROR) << reason;
   state_ = kError;
-  client_->OnError();
+  client_->OnError(reason);
 }
 
 bool VideoCaptureDeviceMac::UpdateCaptureResolution() {
diff --git a/media/video/capture/video_capture_device.h b/media/video/capture/video_capture_device.h
index c02dcc1..a3cabad 100644
--- a/media/video/capture/video_capture_device.h
+++ b/media/video/capture/video_capture_device.h
@@ -180,8 +180,8 @@ class MEDIA_EXPORT VideoCaptureDevice {
                                           int frame_rate) = 0;
 
     // An error has occurred that cannot be handled and VideoCaptureDevice must
-    // be StopAndDeAllocate()-ed.
-    virtual void OnError() = 0;
+    // be StopAndDeAllocate()-ed. |reason| is a text description of the error.
+    virtual void OnError(const std::string& reason) = 0;
   };
 
   // Creates a VideoCaptureDevice object.
diff --git a/media/video/capture/video_capture_device_unittest.cc b/media/video/capture/video_capture_device_unittest.cc
index 6a765e1..735a96a 100644
--- a/media/video/capture/video_capture_device_unittest.cc
+++ b/media/video/capture/video_capture_device_unittest.cc
@@ -69,7 +69,7 @@ class MockClient : public media::VideoCaptureDevice::Client {
   explicit MockClient(base::Callback<void(const VideoCaptureFormat&)> frame_cb)
       : main_thread_(base::MessageLoopProxy::current()), frame_cb_(frame_cb) {}
 
-  virtual void OnError() OVERRIDE {
+  virtual void OnError(const std::string& error_message) OVERRIDE {
     OnErr();
   }
 
diff --git a/media/video/capture/win/video_capture_device_mf_win.cc b/media/video/capture/win/video_capture_device_mf_win.cc
index f4007fa..de199c2 100644
--- a/media/video/capture/win/video_capture_device_mf_win.cc
+++ b/media/video/capture/win/video_capture_device_mf_win.cc
@@ -9,6 +9,7 @@
 
 #include "base/lazy_instance.h"
 #include "base/memory/ref_counted.h"
+#include "base/strings/stringprintf.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/win/scoped_co_mem.h"
@@ -432,9 +433,10 @@ void VideoCaptureDeviceMFWin::OnIncomingCapturedFrame(
 }
 
 void VideoCaptureDeviceMFWin::OnError(HRESULT hr) {
-  DLOG(ERROR) << "VideoCaptureDeviceMFWin: " << std::hex << hr;
+  std::string log_msg = base::StringPrintf("VideoCaptureDeviceMFWin: %x", hr);
+  DLOG(ERROR) << log_msg;
   if (client_.get())
-    client_->OnError();
+    client_->OnError(log_msg);
 }
 
 }  // namespace media
diff --git a/media/video/capture/win/video_capture_device_win.cc b/media/video/capture/win/video_capture_device_win.cc
index 48dd3da..13d4d48 100644
--- a/media/video/capture/win/video_capture_device_win.cc
+++ b/media/video/capture/win/video_capture_device_win.cc
@@ -590,10 +590,10 @@ bool VideoCaptureDeviceWin::CreateCapabilityMap() {
   return !capabilities_.empty();
 }
 
-void VideoCaptureDeviceWin::SetErrorState(const char* reason) {
+void VideoCaptureDeviceWin::SetErrorState(const std::string& reason) {
   DCHECK(CalledOnValidThread());
   DVLOG(1) << reason;
   state_ = kError;
-  client_->OnError();
+  client_->OnError(reason);
 }
 }  // namespace media
diff --git a/media/video/capture/win/video_capture_device_win.h b/media/video/capture/win/video_capture_device_win.h
index 164c01c..8c9e546 100644
--- a/media/video/capture/win/video_capture_device_win.h
+++ b/media/video/capture/win/video_capture_device_win.h
@@ -59,7 +59,7 @@ class VideoCaptureDeviceWin
   virtual void FrameReceived(const uint8* buffer, int length);
 
   bool CreateCapabilityMap();
-  void SetErrorState(const char* reason);
+  void SetErrorState(const std::string& reason);
 
   Name device_name_;
   InternalState state_;