Browser-wide audio mirroring for TabCapture API

content/browser/renderer_host/media/web_contents_video_capture_device.cc

Index: content/browser/renderer_host/media/web_contents_video_capture_device.cc
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 cfb1e8e539d9e597454f6a2754e90459f7bf3701..e22e7b85c2f9e0b83f612704091a7f4fc5232ce9 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
@@ -52,6 +52,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/string_number_conversions.h"
 #include "base/string_piece.h"
+#include "base/string_util.h"
 #include "base/stringprintf.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread.h"
@@ -62,6 +63,7 @@
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_observer.h"
+#include "content/public/common/media_stream_request.h"
 #include "media/base/bind_to_loop.h"
 #include "media/video/capture/video_capture_types.h"
 #include "skia/ext/image_operations.h"
@@ -970,7 +972,13 @@ WebContentsVideoCaptureDevice::~WebContentsVideoCaptureDevice() {
 
 // static
 media::VideoCaptureDevice* WebContentsVideoCaptureDevice::Create(
-    const std::string& device_id) {
+    const std::string& device_id_param) {
+  DCHECK(StartsWithASCII(device_id_param,
+                         content::kMediaStreamTabDeviceScheme, true));
+  const std::string device_id = device_id_param.substr(
+    strlen(content::kMediaStreamTabDeviceScheme),
+    device_id_param.length());
+
   // Parse device_id into render_process_id and render_view_id.
   const size_t sep_pos = device_id.find(':');
   if (sep_pos == std::string::npos) {