Split FakeVideoCaptureDevice into classes with single responsibility

media/capture/video/fake_video_capture_device_factory.h

Index: media/capture/video/fake_video_capture_device_factory.h
diff --git a/media/capture/video/fake_video_capture_device_factory.h b/media/capture/video/fake_video_capture_device_factory.h
index ef510573d645b0c9455e9e1a139b9ee482324bc7..7fb0597fe7e99f61ae5def6f4ce500a1b4b738a3 100644
--- a/media/capture/video/fake_video_capture_device_factory.h
+++ b/media/capture/video/fake_video_capture_device_factory.h
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Implementation of a fake VideoCaptureDeviceFactory class.
-
 #ifndef MEDIA_CAPTURE_VIDEO_FAKE_VIDEO_CAPTURE_DEVICE_FACTORY_H_
 #define MEDIA_CAPTURE_VIDEO_FAKE_VIDEO_CAPTURE_DEVICE_FACTORY_H_
 
@@ -12,8 +10,14 @@
 
 namespace media {
 
-// Extension of VideoCaptureDeviceFactory to create and manipulate fake devices,
-// not including file-based ones.
+// Implementation of VideoCaptureDeviceFactory that creates fake devices
+// that generate test output frames.
+// By default, the factory has one device outputting I420.
+// When increasing the number of devices using set_number_of_devices(), the
+// second device will use Y16, and any devices beyond that will use I420.
+// By default, the delivery mode of all devices is USE_OWN_BUFFERS.
+// This, as well as other parameters, can be changed using command-line flags.
+// See implementation of method ParseCommandLine() for details.
 class CAPTURE_EXPORT FakeVideoCaptureDeviceFactory
     : public VideoCaptureDeviceFactory {
  public:
@@ -41,7 +45,7 @@ class CAPTURE_EXPORT FakeVideoCaptureDeviceFactory
   void ParseCommandLine();
 
   int number_of_devices_;
-  FakeVideoCaptureDevice::BufferOwnership fake_vcd_ownership_;
+  FakeVideoCaptureDeviceMaker::DeliveryMode delivery_mode_;
   float frame_rate_;
   bool command_line_parsed_ = false;
 };