Add VideoCaptureDevice::GetDeviceSupportedFormats to interface + implementation for Linux and Fake

media/video/capture/video_capture_device.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.
 //
 // VideoCaptureDevice is the abstract base class for realizing video capture
 // device support in Chromium. It provides the interface for OS dependent
 // implementations.
 // The class is created and functions are invoked on a thread owned by
 // VideoCaptureManager. Capturing is done on other threads, depending on the OS
 // specific implementation.
@@ skipping 163 matching lines @@
     // be StopAndDeAllocate()-ed.
     virtual void OnError() = 0;
 
     // Called when VideoCaptureDevice::AllocateAndStart() has been called to
     // inform of the resulting frame size.
     virtual void OnFrameInfo(const VideoCaptureCapability& info) = 0;
 
     // Called when the native resolution of VideoCaptureDevice has been changed
     // and it needs to inform its client of the new frame size.
     virtual void OnFrameInfoChanged(const VideoCaptureCapability& info) {};
+
+    // Called when VideoCaptureDevice::GetDeviceSupportedFormats() has been
+    // called, to reply with the the resulting device capabilities.
+    virtual void OnDeviceSupportedFormatsEnumerated(
+        const VideoCaptureFormats& formats) {};
   };
   // Creates a VideoCaptureDevice object.
   // Return NULL if the hardware is not available.
   static VideoCaptureDevice* Create(const Name& device_name);
   virtual ~VideoCaptureDevice();
 
   // Gets the names of all video capture devices connected to this computer.
   static void GetDeviceNames(Names* device_names);
 
   // Prepare the camera for use. After this function has been called no other
   // applications can use the camera. On completion EventHandler::OnFrameInfo()
   // is called informing of the resulting resolution and frame rate.
   // StopAndDeAllocate() must be called before the object is deleted.
   virtual void AllocateAndStart(
       const VideoCaptureCapability& capture_format,
       scoped_ptr<EventHandler> client) = 0;
 
   // Deallocates the camera, possibly asynchronously.
   //
   // This call requires the device to do the following things, eventually: put
   // camera hardware into a state where other applications could use it, free
   // the memory associated with capture, and delete the |client| pointer passed
   // into AllocateAndStart.
   //
   // If deallocation is done asynchronously, then the device implementation must
   // ensure that a subsequent AllocateAndStart() operation targeting the same ID
   // would be sequenced through the same task runner, so that deallocation
   // happens first.
   virtual void StopAndDeAllocate() = 0;
+
+  // Gets the supported video capture formats, if operation is supported by the
+  // driver, for a particular video capture device. This operation may be called
+  // before or after AllocateAndStart, and it may take into account the current
+  // state of the device, f.i. an already opened device might see supported
+  // formats limited etc.
+  virtual void GetDeviceSupportedFormats(scoped_ptr<EventHandler> client) {};

[perkj_chrome, 2013/09/25 07:58:41]

Instead of |client| beeing an EventHandler - it might be easier to just let it
be of type base::CallBack, see MediaRequestResponseCallback for an example.
Otherwise you will have to rethink what a |client| is and when it is provided -
ie - before AllocateAndStart. You don't want to delete the VCC just because you
wanted to get the available formats.

You should also make sure GetDevicesSupportedFormats always return- even if an
error occur or the function is not implemented. It will be very hard to use
unless you know that you always get a result.

Have you thought about how this will be used? 

[mcasas, 2013/10/02 08:13:23]

Done.

 };
 
 // VideoCaptureDevice1 is a bridge to an older API against which
 // VideoCaptureDevices were implemented. Differences between VideoCaptureDevice
 // (new style) and VideoCaptureDevice1 (old style) are as follows:
 //
 // [1] The Stop+DeAllocate calls are merged in the new style.
 // [2] The Allocate+Start calls are merged in the new style.
 // [3] New style devices own their EventHandler* pointers, allowing handlers to
 //     remain valid even after the device is stopped. Whereas old style devices
@@ skipping 37 matching lines @@
   virtual const Name& device_name() = 0;
 
  private:
   // The device client which proxies device events to the controller.
   scoped_ptr<EventHandler> client_;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_VIDEO_CAPTURE_VIDEO_CAPTURE_DEVICE_H_