[Mojo Video Capture] Simplify media::VideoCaptureDevice::Client:Buffer to a struct

media/capture/video/fake_video_capture_device.cc

Index: media/capture/video/fake_video_capture_device.cc
diff --git a/media/capture/video/fake_video_capture_device.cc b/media/capture/video/fake_video_capture_device.cc
index 8ea60bccc8efd1f1e11626a75de38f7e8bc173bf..7ecc3f416c3d9d830e0662b89afde53f2bad0d79 100644
--- a/media/capture/video/fake_video_capture_device.cc
+++ b/media/capture/video/fake_video_capture_device.cc
@@ -320,16 +320,18 @@ void FakeVideoCaptureDevice::CaptureUsingClientBuffers(
   DCHECK(thread_checker_.CalledOnValidThread());
 
   const int arbitrary_frame_feedback_id = 0;
-  std::unique_ptr<VideoCaptureDevice::Client::Buffer> capture_buffer(
+  VideoCaptureDevice::Client::Buffer capture_buffer =
       client_->ReserveOutputBuffer(
           capture_format_.frame_size, capture_format_.pixel_format,
-          capture_format_.pixel_storage, arbitrary_frame_feedback_id));
-  DLOG_IF(ERROR, !capture_buffer) << "Couldn't allocate Capture Buffer";
-  DCHECK(capture_buffer->data()) << "Buffer has NO backing memory";
+          capture_format_.pixel_storage, arbitrary_frame_feedback_id);
+  DLOG_IF(ERROR, !capture_buffer.is_valid())
+      << "Couldn't allocate Capture Buffer";
+  auto buffer_access = capture_buffer.access_provider->GetReadWriteAccess();
+  DCHECK(buffer_access->data()) << "Buffer has NO backing memory";
 
   DCHECK_EQ(PIXEL_STORAGE_CPU, capture_format_.pixel_storage);
-  uint8_t* data_ptr = static_cast<uint8_t*>(capture_buffer->data());
-  memset(data_ptr, 0, capture_buffer->mapped_size());
+  uint8_t* data_ptr = buffer_access->data();
+  memset(data_ptr, 0, buffer_access->mapped_size());
   DrawPacman(capture_format_.pixel_format, data_ptr, elapsed_time_,
              fake_capture_rate_, capture_format_.frame_size, current_zoom_);