Log error messages in windows video capture

content/browser/renderer_host/media/video_capture_controller.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/renderer_host/media/video_capture_controller.h"
 
 #include <map>
 #include <set>
 
 #include "base/bind.h"
@@ skipping 498 matching lines @@
           &VideoCaptureController::DoIncomingCapturedVideoFrameOnIOThread,
           controller_,
           buffer,
           buffer_format,
           frame,
           timestamp));
 }
 
 void VideoCaptureController::VideoCaptureDeviceClient::OnError(
     const std::string& reason) {
+  const std::string last_error_message =
+      logging::SystemErrorCodeToString(logging::GetLastSystemErrorCode());
+  const std::string log_message =
+      reason + ", OS message: " + last_error_message;
+  DLOG(ERROR) << log_message;

[tommi (sloooow) - chröme, 2014/08/27 14:46:18]

log_message could be a std::ostringstream which would reduce the amount of
std::string objects being created as a result of using operator+().

[magjed_chromium, 2014/08/27 17:03:27]

Done.

   MediaStreamManager::SendMessageToNativeLog(
-      "Error on video capture: " + reason);
+      "Error on video capture: " + log_message);

[tommi (sloooow) - chröme, 2014/08/27 14:46:18]

"Error on video capture: " could be made the first part of log_message which
would reduce one more std::string.

[magjed_chromium, 2014/08/27 17:03:27]

Done.

   BrowserThread::PostTask(BrowserThread::IO,
       FROM_HERE,
       base::Bind(&VideoCaptureController::DoErrorOnIOThread, controller_));
 }
 
 void VideoCaptureController::VideoCaptureDeviceClient::OnLog(
     const std::string& message) {
   MediaStreamManager::SendMessageToNativeLog("Video capture: " + message);
 }
 
@@ skipping 145 matching lines @@
   }
   return NULL;
 }
 
 int VideoCaptureController::GetClientCount() {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   return controller_clients_.size();
 }
 
 }  // namespace content