Add AshDesktopMediaList and enable Desktop Capture API on Chrome OS.

content/browser/renderer_host/media/desktop_capture_device_ash.cc

Index: content/browser/renderer_host/media/desktop_capture_device_ash.cc
diff --git a/content/browser/renderer_host/media/desktop_capture_device_ash.cc b/content/browser/renderer_host/media/desktop_capture_device_ash.cc
index 8fd7cfa9ad4fad39ea248e24043ec3fa1580792d..b720f38ece2ed9c6eb52abc2663c8d4f04dfdf45 100644
--- a/content/browser/renderer_host/media/desktop_capture_device_ash.cc
+++ b/content/browser/renderer_host/media/desktop_capture_device_ash.cc
@@ -83,7 +83,7 @@ class DesktopVideoCaptureMachine
   base::Timer timer_;
 
   // The id of the window being captured.
-  const DesktopMediaID& window_id_;
+  DesktopMediaID window_id_;
 
   // Makes all the decisions about which frames to copy, and how.
   scoped_refptr<ThreadSafeCaptureOracle> oracle_proxy_;
@@ -145,14 +145,17 @@ void DesktopVideoCaptureMachine::Stop() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   // Stop observing window events.
-  if (desktop_window_)
+  if (desktop_window_) {
     desktop_window_->RemoveObserver(this);
+    desktop_window_ = NULL;
+  }
 
   // Stop observing compositor updates.
   if (desktop_layer_) {
     ui::Compositor* compositor = desktop_layer_->GetCompositor();
     if (compositor)
       compositor->RemoveObserver(this);
+    desktop_layer_ = NULL;
   }
 
   // Stop timer.
@@ -275,13 +278,11 @@ void DesktopVideoCaptureMachine::OnWindowBoundsChanged(
 }
 
 void DesktopVideoCaptureMachine::OnWindowDestroyed(aura::Window* window) {
-  DCHECK(desktop_window_ && window == desktop_window_);
-  desktop_window_ = NULL;
-  desktop_layer_ = NULL;
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
-  // Post task to stop capture on UI thread.
-  BrowserThread::PostTask(BrowserThread::UI, FROM_HERE, base::Bind(
-      &DesktopVideoCaptureMachine::Stop, AsWeakPtr()));
+  Stop();
+
+  oracle_proxy_->ReportError();
 }
 
 void DesktopVideoCaptureMachine::OnCompositingEnded(