[Mojo Video Capture] Split OnIncomingCapturedVideoFrame() to OnNewBuffer() and OnFrameReadyInBuffer(

content/browser/renderer_host/media/video_capture_controller.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.
-//
-// VideoCaptureController is the glue between a VideoCaptureDevice and all
-// VideoCaptureHosts that have connected to it. A controller exists on behalf of
-// one (and only one) VideoCaptureDevice; both are owned by the
-// VideoCaptureManager.
-//
-// The VideoCaptureController is responsible for:
-//
-//   * Allocating and keeping track of shared memory buffers, and filling them
-//     with I420 video frames for IPC communication between VideoCaptureHost (in
-//     the browser process) and VideoCaptureMessageFilter (in the renderer
-//     process).
-//   * Broadcasting the events from a single VideoCaptureDevice, fanning them
-//     out to multiple clients.
-//   * Keeping track of the clients on behalf of the VideoCaptureManager, making
-//     it possible for the Manager to delete the Controller and its Device when
-//     there are no clients left.
-//
-// Interactions between VideoCaptureController and other classes:
-//
-//   * VideoCaptureController indirectly observes a VideoCaptureDevice
-//     by means of its proxy, VideoCaptureDeviceClient, which implements
-//     the VideoCaptureDevice::Client interface. The proxy forwards
-//     observed events to the VideoCaptureController on the IO thread.
-//   * A VideoCaptureController interacts with its clients (VideoCaptureHosts)
-//     via the VideoCaptureControllerEventHandler interface.
-//   * Conversely, a VideoCaptureControllerEventHandler (typically,
-//     VideoCaptureHost) will interact directly with VideoCaptureController to
-//     return leased buffers by means of the ReturnBuffer() public method of
-//     VCC.
-//   * VideoCaptureManager (which owns the VCC) interacts directly with
-//     VideoCaptureController through its public methods, to add and remove
-//     clients.
-//
-// VideoCaptureController is not thread safe and operates on the IO thread only.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_CONTROLLER_H_
 #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_CONTROLLER_H_
 
 #include <list>
 #include <memory>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/process/process.h"
 #include "content/browser/renderer_host/media/video_capture_controller_event_handler.h"
 #include "content/common/content_export.h"
 #include "content/common/media/video_capture.h"
 #include "media/capture/video/video_frame_receiver.h"
 #include "media/capture/video_capture_types.h"
 
-namespace media {
-class FrameBufferPool;
-}
-
 namespace content {
 
+// Implementation of media::VideoFrameReceiver that distributes received frames
+// to potentially multiple connected clients.
 class CONTENT_EXPORT VideoCaptureController : public media::VideoFrameReceiver {
  public:
   VideoCaptureController();
   ~VideoCaptureController() override;
 
   base::WeakPtr<VideoCaptureController> GetWeakPtrForIOThread();
 
-  // A FrameBufferPool may optionally be set in order to receive notifications
-  // when a frame is starting to get consumed and has finished getting consumed.
-  void SetFrameBufferPool(
-      std::unique_ptr<media::FrameBufferPool> frame_buffer_pool);
-
   // Factory code creating instances of VideoCaptureController may optionally
   // set a VideoFrameConsumerFeedbackObserver. Setting the observer is done in
   // this method separate from the constructor to allow clients to create and
   // use instances before they can provide the observer. (This is the case with
   // VideoCaptureManager).
   void SetConsumerFeedbackObserver(
       std::unique_ptr<media::VideoFrameConsumerFeedbackObserver> observer);
 
   // Start video capturing and try to use the resolution specified in |params|.
   // Buffers will be shared to the client as necessary. The client will continue
@@ skipping 37 matching lines @@
   void ReturnBuffer(VideoCaptureControllerID id,
                     VideoCaptureControllerEventHandler* event_handler,
                     int buffer_id,
                     double consumer_resource_utilization);
 
   const media::VideoCaptureFormat& GetVideoCaptureFormat() const;
 
   bool has_received_frames() const { return has_received_frames_; }
 
   // Implementation of media::VideoFrameReceiver interface:
-  void OnIncomingCapturedVideoFrame(
-      media::VideoCaptureDevice::Client::Buffer buffer,
-      scoped_refptr<media::VideoFrame> frame) override;
+  void OnNewBufferHandle(
+      int buffer_id,
+      std::unique_ptr<media::VideoCaptureDevice::Client::Buffer::HandleProvider>
+          handle_provider) override;
+  void OnFrameReadyInBuffer(
+      int buffer_id,
+      int frame_feedback_id,
+      std::unique_ptr<
+          media::VideoCaptureDevice::Client::Buffer::ScopedAccessPermission>
+          buffer_read_permission,
+      media::mojom::VideoFrameInfoPtr frame_info) override;
+  void OnBufferRetired(int buffer_id) override;
   void OnError() override;
   void OnLog(const std::string& message) override;
-  void OnBufferRetired(int buffer_id) override;
 
  private:
   struct ControllerClient;
   typedef std::list<std::unique_ptr<ControllerClient>> ControllerClients;
 
   class BufferContext {
    public:
     BufferContext(
         int buffer_context_id,
         int buffer_id,
         media::VideoFrameConsumerFeedbackObserver* consumer_feedback_observer,
-        media::FrameBufferPool* frame_buffer_pool);
+        mojo::ScopedSharedBufferHandle handle);
     ~BufferContext();
-    BufferContext(const BufferContext& other);
-    BufferContext& operator=(const BufferContext& other);
+    BufferContext(BufferContext&& other);
+    BufferContext& operator=(BufferContext&& other);
     int buffer_context_id() const { return buffer_context_id_; }
     int buffer_id() const { return buffer_id_; }
     bool is_retired() const { return is_retired_; }
     void set_is_retired() { is_retired_ = true; }
     void set_frame_feedback_id(int id) { frame_feedback_id_ = id; }
     void set_consumer_feedback_observer(
         media::VideoFrameConsumerFeedbackObserver* consumer_feedback_observer) {
       consumer_feedback_observer_ = consumer_feedback_observer;
     }
-    void set_frame_buffer_pool(media::FrameBufferPool* frame_buffer_pool) {
-      frame_buffer_pool_ = frame_buffer_pool;
+    void set_read_permission(
+        std::unique_ptr<
+            media::VideoCaptureDevice::Client::Buffer::ScopedAccessPermission>
+            buffer_read_permission) {
+      buffer_read_permission_ = std::move(buffer_read_permission);
     }
     void RecordConsumerUtilization(double utilization);
     void IncreaseConsumerCount();
     void DecreaseConsumerCount();
-    bool HasZeroConsumerHoldCount();
+    bool HasZeroConsumerHoldCount() const;
+    bool HasConsumers() const;
+    mojo::ScopedSharedBufferHandle CreateHandleCopy();

[mcasas, 2017/02/16 22:35:56]

nit: s/CreateHandleCopy/CloneHandle/ ?

[chfremer, 2017/02/16 23:37:57]

Done.

 
    private:
     int buffer_context_id_;
     int buffer_id_;
     bool is_retired_;
     int frame_feedback_id_;
     media::VideoFrameConsumerFeedbackObserver* consumer_feedback_observer_;
-    media::FrameBufferPool* frame_buffer_pool_;
+    mojo::ScopedSharedBufferHandle buffer_handle_;
     double max_consumer_utilization_;
     int consumer_hold_count_;
+    std::unique_ptr<
+        media::VideoCaptureDevice::Client::Buffer::ScopedAccessPermission>
+        buffer_read_permission_;
   };
 
   // Find a client of |id| and |handler| in |clients|.
   ControllerClient* FindClient(VideoCaptureControllerID id,
                                VideoCaptureControllerEventHandler* handler,
                                const ControllerClients& clients);
 
   // Find a client of |session_id| in |clients|.
   ControllerClient* FindClient(int session_id,
                                const ControllerClients& clients);
 
   std::vector<BufferContext>::iterator FindBufferContextFromBufferContextId(
       int buffer_context_id);
   std::vector<BufferContext>::iterator FindUnretiredBufferContextFromBufferId(

[mcasas, 2017/02/16 22:35:56]

This is totally unrelated to this CL, but wdyt about
s/FindUnretiredBufferContextFromBufferId
FindActiveBufferContextFromBufferId/  ?

In the sense of Buffer Contexts can be Active/Retired,
more than active/retired....

[chfremer, 2017/02/16 23:37:57]

I considered your proposal, but ended up deciding it may be better to keep it as
is.
The reason is that introducing the term "Active" requires an explanation
somewhere saying that a BufferContext can be either Active or Retired, i.e.
these are mutually exclusive states. The best way to express that in code (to
avoid settling for a comment) would be using an enum class.
On the other hand, by using the term "Unretired" it is fairly clear that this
means that the |is_retired_| flag is not set, and we can do this with just a
boolean and no comment or enum class needed.

       int buffer_id);
 
   void OnClientFinishedConsumingBuffer(ControllerClient* client,
                                        int buffer_id,
                                        double consumer_resource_utilization);
   void ReleaseBufferContext(
       const std::vector<BufferContext>::iterator& buffer_state_iter);
 
-  std::unique_ptr<media::FrameBufferPool> frame_buffer_pool_;
-
   std::unique_ptr<media::VideoFrameConsumerFeedbackObserver>
       consumer_feedback_observer_;
 
   std::vector<BufferContext> buffer_contexts_;
 
   // All clients served by this controller.
   ControllerClients controller_clients_;
 
   // Takes on only the states 'STARTED' and 'ERROR'. 'ERROR' is an absorbing
   // state which stops the flow of data to clients.
   VideoCaptureState state_;
 
   int next_buffer_context_id_ = 0;
 
   // True if the controller has received a video frame from the device.
   bool has_received_frames_;
 
   media::VideoCaptureFormat video_capture_format_;
 
   base::WeakPtrFactory<VideoCaptureController> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(VideoCaptureController);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_CONTROLLER_H_