-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 CameraVideoService {

[alhaad1, 2015/10/02 06:33:27]

Could we call it just CameraService? There is nothing video specific about this.
We could use it to capture images as well. (And we could conceivably add finer
control later) 

[gautham, 2015/10/02 22:29:11]

Done.

+  GetVideoFrames() => (handle<data_pipe_consumer>? content);

[alhaad1, 2015/10/02 06:33:27]

This could be GetLatestFrame?

Also, do you think it would be better if we share the struct Photo between the
two?

[gautham, 2015/10/02 22:29:11]

I'm hoping we'll fix the ImageDecoder to work with a streaming data_pipe and
would not have not close/re-open the handle on the sender side. After that we'd
need the return value to be a data_pipe. 

+};