Update Bind to match its comments and always capture by value.

talk/media/webrtc/webrtcvideocapturer.cc

 /*
  * libjingle
  * Copyright 2011 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  *  1. Redistributions of source code must retain the above copyright notice,
  *     this list of conditions and the following disclaimer.
  *  2. Redistributions in binary form must reproduce the above copyright notice,
@@ skipping 365 matching lines @@
   if (start_thread_->IsCurrent()) {
     SignalFrameCapturedOnStartThread(sample);
   } else {
     // This currently happens on with at least VideoCaptureModuleV4L2 and
     // possibly other implementations of WebRTC's VideoCaptureModule.
     // In order to maintain the threading contract with the upper layers and
     // consistency with other capturers such as in Chrome, we need to do a
     // thread hop.
     // Note that Stop() can cause the async invoke call to be cancelled.
     async_invoker_->AsyncInvoke<void>(start_thread_,
-        // Note that this results in a shallow copying of the frame.
+        // Note that Bind captures by value, so there's an intermediate copy
+        // of sample.
         rtc::Bind(&WebRtcVideoCapturer::SignalFrameCapturedOnStartThread,
                   this, sample));
   }
 }
 
 void WebRtcVideoCapturer::OnCaptureDelayChanged(const int32_t id,
                                                 const int32_t delay) {
   LOG(LS_INFO) << "Capture delay changed to " << delay << " ms";
 }
 
 void WebRtcVideoCapturer::SignalFrameCapturedOnStartThread(
-    const webrtc::VideoFrame frame) {
+    const webrtc::VideoFrame& frame) {
   // This can only happen between Start() and Stop().
   RTC_DCHECK(start_thread_);
   RTC_DCHECK(start_thread_->IsCurrent());
   RTC_DCHECK(async_invoker_);
 
   ++captured_frames_;
   // Log the size and pixel aspect ratio of the first captured frame.
   if (1 == captured_frames_) {
     LOG(LS_INFO) << "Captured frame size "
                  << frame.width() << "x" << frame.height()
@@ skipping 26 matching lines @@
   // Convert units from VideoFrame RenderTimeMs to CapturedFrame (nanoseconds).
   time_stamp = sample.render_time_ms() * rtc::kNumNanosecsPerMillisec;
   data_size = rtc::checked_cast<uint32_t>(length);
   data = buffer;
   rotation = sample.rotation();
 }
 
 }  // namespace cricket
 
 #endif  // HAVE_WEBRTC_VIDEO