Add AshDesktopMediaList and enable Desktop Capture API on Chrome OS.

ui/snapshot/snapshot_win.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 "ui/snapshot/snapshot_win.h"
 
 #include "base/win/scoped_gdi_object.h"
 #include "base/win/scoped_hdc.h"
 #include "base/win/scoped_select_object.h"
 #include "ui/gfx/codec/png_codec.h"
@@ skipping 85 matching lines @@
                         png_representation);
 
   ReleaseDC(window_handle, window_hdc);
 
   return true;
 }
 
 }  // namespace internal
 
 #if !defined(USE_AURA)
+
 bool GrabViewSnapshot(gfx::NativeView view_handle,
                       std::vector<unsigned char>* png_representation,
                       const gfx::Rect& snapshot_bounds) {
   return GrabWindowSnapshot(view_handle, png_representation, snapshot_bounds);
 }
 
 bool GrabWindowSnapshot(gfx::NativeWindow window_handle,
                         std::vector<unsigned char>* png_representation,
                         const gfx::Rect& snapshot_bounds) {
   DCHECK(window_handle);
   return internal::GrabHwndSnapshot(window_handle, snapshot_bounds,
                                     png_representation);
 }
+
+SNAPSHOT_EXPORT void GrapWindowSnapshotAsync(
+    gfx::NativeWindow window,
+    const gfx::Rect& snapshot_bounds,
+    const gfx::Size& target_size,
+    scoped_refptr<base::TaskRunner> background_task_runner,
+    GrapWindowSnapshotAsyncCallback callback) {
+  NOTIMPLEMENTED();
+}
+
 #endif  // !defined(USE_AURA)
 
 }  // namespace ui