VideoCapture: migrate last Renderer-->Host msg and start Host-->Renderer migration

content/browser/renderer_host/media/video_capture_host.h

 // 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.
 //
 // VideoCaptureHost serves video capture related messages from
 // VideoCaptureMessageFilter which lives inside the render process.
 //
 // This class is owned by RenderProcessHostImpl, and instantiated on UI
 // thread, but all other operations and method calls happen on IO thread.
 //
 // Here's an example of a typical IPC dialog for video capture:
 //
 //   Renderer                             VideoCaptureHost
 //      |                                        |
 //      |  --------- StartCapture -------->      |
-//      | < VideoCaptureMsg_StateChanged         |
-//      |        (VIDEO_CAPTURE_STATE_STARTED)   |
+//      | <------ VideoCaptureObserver   ------  |
+//      |         ::StateChanged(STARTED)        |
 //      | < VideoCaptureMsg_NewBuffer(1)         |
 //      | < VideoCaptureMsg_NewBuffer(2)         |
 //      | < VideoCaptureMsg_NewBuffer(3)         |
 //      |                                        |
 //      | < VideoCaptureMsg_BufferReady(1)       |
 //      | < VideoCaptureMsg_BufferReady(2)       |
-//      | VideoCaptureHostMsg_BufferReady(1) >   |
+//      | -------- ReleaseBuffer(1) --------->   |
 //      | < VideoCaptureMsg_BufferReady(3)       |
-//      | VideoCaptureHostMsg_BufferReady(2) >   |
+//      | -------- ReleaseBuffer(2) --------->   |
 //      | < VideoCaptureMsg_BufferReady(1)       |
-//      | VideoCaptureHostMsg_BufferReady(3) >   |
+//      | -------- ReleaseBuffer(3) --------->   |
 //      | < VideoCaptureMsg_BufferReady(2)       |
-//      | VideoCaptureHostMsg_BufferReady(1) >   |
+//      | -------- ReleaseBuffer(1) --------->   |
 //      |             ...                        |
 //      | < VideoCaptureMsg_BufferReady(3)       |
 //      |                                        |
 //      |             ... (resolution change)    |
 //      | < VideoCaptureMsg_FreeBuffer(1)        |  Buffers are re-allocated
 //      | < VideoCaptureMsg_NewBuffer(4)         |  with a larger size, as
 //      | < VideoCaptureMsg_BufferReady(4)       |  needed.
-//      | VideoCaptureHostMsg_BufferReady(2) >   |
+//      | -------- ReleaseBuffer(2) --------->   |
 //      | < VideoCaptureMsg_FreeBuffer(2)        |
 //      | < VideoCaptureMsg_NewBuffer(5)         |
 //      | < VideoCaptureMsg_BufferReady(5)       |
 //      |             ...                        |
 //      |                                        |
 //      | < VideoCaptureMsg_BufferReady          |
 //      |  --------- StopCapture --------->      |
-//      | VideoCaptureHostMsg_BufferReady >      |
-//      | < VideoCaptureMsg_StateChanged         |
-//      |         (VIDEO_CAPTURE_STATE_STOPPED)  |
+//      | -------- ReleaseBuffer(n) --------->   |
+//      | <------ VideoCaptureObserver   ------  |
+//      |         ::StateChanged(STOPPED)        |
 //      v                                        v
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_HOST_H_
 #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_HOST_H_
 
 #include <map>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
@@ skipping 39 matching lines @@
   friend class BrowserThread;
   friend class base::DeleteHelper<VideoCaptureHost>;
   friend class MockVideoCaptureHost;
   friend class VideoCaptureHostTest;
 
   void DoError(VideoCaptureControllerID id);
   void DoEnded(VideoCaptureControllerID id);
 
   ~VideoCaptureHost() override;
 
-  // IPC message handlers.
-  void OnRendererFinishedWithBuffer(int device_id,
-                                    int buffer_id,
-                                    const gpu::SyncToken& sync_token,
-                                    double consumer_resource_utilization);
-
   // mojom::VideoCaptureHost implementation
   void Start(int32_t device_id,
              int32_t session_id,
-             const media::VideoCaptureParams& params) override;
+             const media::VideoCaptureParams& params,
+             mojom::VideoCaptureObserverPtr observer) override;
   void Stop(int32_t device_id) override;
   void Pause(int32_t device_id) override;
   void Resume(int32_t device_id,
               int32_t session_id,
               const media::VideoCaptureParams& params) override;
   void RequestRefreshFrame(int32_t device_id) override;
+  void ReleaseBuffer(int32_t device_id,
+                     int32_t buffer_id,
+                     const gpu::SyncToken& sync_token,
+                     double consumer_resource_utilization) override;
   void GetDeviceSupportedFormats(
       int32_t device_id,
       int32_t session_id,
       const GetDeviceSupportedFormatsCallback& callback) override;
   void GetDeviceFormatsInUse(
       int32_t device_id,
       int32_t session_id,
       const GetDeviceFormatsInUseCallback& callback) override;
 
   void OnControllerAdded(
       int device_id,
       const base::WeakPtr<VideoCaptureController>& controller);
 
   // Deletes the controller and notifies the VideoCaptureManager. |on_error| is
   // true if this is triggered by VideoCaptureControllerEventHandler::OnError.
   void DeleteVideoCaptureController(VideoCaptureControllerID controller_id,
                                     bool on_error);
 
   MediaStreamManager* const media_stream_manager_;
 
   // A map of VideoCaptureControllerID to the VideoCaptureController to which it
   // is connected. An entry in this map holds a null controller while it is in
   // the process of starting.
   std::map<VideoCaptureControllerID, base::WeakPtr<VideoCaptureController>>
       controllers_;
 
+  // VideoCaptureObservers map, each one is used and should be valid between
+  // Start() and the corresponding Stop().
+  std::map<int32_t, mojom::VideoCaptureObserverPtr> observers_;

[chfremer, 2016/10/10 18:57:19]

Unclear what the int32_t parameter is.
device_id?
session_id
controller_id?

As an arbitrary example, if it was device_id, I recommend expressing that by
naming the member field either "observers_by_device_id_" or
"device_id_to_observer_map_".

[mcasas, 2016/10/10 19:39:44]

The first or the last one :) 
device_id == controller_id is an invariant of this class
(quite unfortunate, but whatever)
I like the last name though., pity about the
line breaks. Done though.

+
   DISALLOW_COPY_AND_ASSIGN(VideoCaptureHost);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_HOST_H_