-Add a mojo service to get video frames from the camera through an android service

mojo/services/camera/public/interfaces/camera.mojom

 // Copyright 2015 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.
 
 [DartPackage="mojo_services"]
 module mojo;
 
 struct Photo {
   // A string to uniquely identify an instance of a |Photo|. This can be used
   // to de-duplicate photos over multiple runs on the camera roll.
@@ skipping 10 matching lines @@
 interface CameraRollService {
   // Updates the snapshot of all photos available. Photos might have been added
   // or removed after the service was started or |Update| was called.
   Update();
   // Get the number of photos available in the current snapshot.
   GetCount() => (uint32 num_photos);
   // Get the photo from the current snapshot at |index|. null will be returned
   // if such an index is out-of-bounds.
   GetPhoto(uint32 index) => (Photo? photo);
 };
+
+// |CameraService| provides access to the device's camera video stream.
+interface CameraService {
+  // Returns the most recent frame captured by the device's camera
+  // in preview mode.
+  GetLatestFrame() => (handle<data_pipe_consumer>? content);
+};