[Mojo Video Capture] Add test coverage for accelerated jpeg decoding

media/capture/video/video_capture_device_client.cc

Index: media/capture/video/video_capture_device_client.cc
diff --git a/media/capture/video/video_capture_device_client.cc b/media/capture/video/video_capture_device_client.cc
index 729c02edc9ed76e7da9eb4f91f5074c86123f2f9..16c66728b0a6140a9d62e6f4144ffbedba1b8789 100644
--- a/media/capture/video/video_capture_device_client.cc
+++ b/media/capture/video/video_capture_device_client.cc
@@ -103,6 +103,7 @@ VideoCaptureDeviceClient::VideoCaptureDeviceClient(
     : receiver_(std::move(receiver)),
       jpeg_decoder_factory_callback_(jpeg_decoder_factory),
       external_jpeg_decoder_initialized_(false),
+      using_external_jpeg_decoder_(false),
       buffer_pool_(std::move(buffer_pool)),
       last_captured_pixel_format_(media::PIXEL_FORMAT_UNKNOWN) {}
 
@@ -281,6 +282,7 @@ void VideoCaptureDeviceClient::OnIncomingCapturedData(
     } else if (status == VideoCaptureJpegDecoder::INIT_PASSED &&
                format.pixel_format == media::PIXEL_FORMAT_MJPEG &&
                rotation == 0 && !flip) {
+      OnUsingExternalJpegDecoder();
       external_jpeg_decoder_->DecodeCapturedData(
           data, length, format, reference_time, timestamp, std::move(buffer));
       return;
@@ -336,9 +338,8 @@ VideoCaptureDeviceClient::ReserveOutputBuffer(
 
   if (!base::ContainsValue(buffer_ids_known_by_receiver_, buffer_id)) {
     receiver_->OnNewBufferHandle(
-        buffer_id,
-        base::MakeUnique<BufferPoolBufferHandleProvider>(buffer_pool_,
-                                                         buffer_id));
+        buffer_id, base::MakeUnique<BufferPoolBufferHandleProvider>(
+                       buffer_pool_, buffer_id));
     buffer_ids_known_by_receiver_.push_back(buffer_id);
   }
 
@@ -426,6 +427,13 @@ double VideoCaptureDeviceClient::GetBufferPoolUtilization() const {
   return buffer_pool_->GetBufferPoolUtilization();
 }
 
+void VideoCaptureDeviceClient::OnUsingExternalJpegDecoder() {
+  if (using_external_jpeg_decoder_)
+    return;
+  using_external_jpeg_decoder_ = true;
+  receiver_->OnStartedUsingGpuDecode();
+}
+
 void VideoCaptureDeviceClient::InitializeI420PlanePointers(
     const gfx::Size& dimensions,
     uint8_t* const data,