media/gpu: Fix scoped_refptr parameter passing.

According to
https://chromium.googlesource.com/chromium/src/+/master/styleguide/c++/c++.md#object-ownership-and-calling-conventions
scoped_refptr should be passed by value, not by reference.

This CL focus on image_processor. More than 200+ lines need to be
fixed in media/gpu:
~/chrome/src/media/gpu$ grep -r "const scoped_refptr<.*>&" | wc
    226    1068   21515

BUG=chromium:906479
TEST=Run VEA VDA unittest on devices (peach_pit and elm)
VEA:
video_encode_accelerator_unittest \
--test_stream_data=bear-320x180.yuv:320:180:1:bear.mp4:100000:30 \
--disable_flush --single-process-tests -v=0

VDA:
video_decode_accelerator_unittest \
--test_stream_data=/usr/local/video/test-25fps.h264:320:240:250:258:\
35:150:1 -v=0 --disable_flush --single-process-tests --ozone-platform=gbm

Change-Id: I963501af745124e565eee4a3febf5a0957d53e10
Reviewed-on: https://chromium-review.googlesource.com/c/1341288Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Commit-Queue: Shuo-Peng Liao <deanliao@google.com>
Cr-Commit-Position: refs/heads/master@{#609197}

media/gpu/image_processor.h

@@ -57,7 +57,7 @@ class ImageProcessor {
   // should pass non-empty |output_dmabuf_fds| and the processed frame will be
   // stored in those buffers. If the number of |output_dmabuf_fds| is not
   // expected, this function will return false.
-  virtual bool Process(const scoped_refptr<VideoFrame>& frame,
+  virtual bool Process(scoped_refptr<VideoFrame> frame,
                        int output_buffer_index,
                        std::vector<base::ScopedFD> output_dmabuf_fds,
                        FrameReadyCB cb) = 0;

media/gpu/v4l2/v4l2_image_processor.cc

@@ -64,7 +64,7 @@ V4L2ImageProcessor::JobRecord::JobRecord() : output_buffer_index(-1) {}
 
 V4L2ImageProcessor::JobRecord::~JobRecord() {}
 
-V4L2ImageProcessor::V4L2ImageProcessor(const scoped_refptr<V4L2Device>& device,
+V4L2ImageProcessor::V4L2ImageProcessor(scoped_refptr<V4L2Device> device,
                                        v4l2_memory input_memory_type,
                                        v4l2_memory output_memory_type)
     : input_format_(PIXEL_FORMAT_UNKNOWN),
@@ -256,7 +256,7 @@ gfx::Size V4L2ImageProcessor::output_allocated_size() const {
   return output_allocated_size_;
 }
 
-bool V4L2ImageProcessor::Process(const scoped_refptr<VideoFrame>& frame,
+bool V4L2ImageProcessor::Process(scoped_refptr<VideoFrame> frame,
                                  int output_buffer_index,
                                  std::vector<base::ScopedFD> output_dmabuf_fds,
                                  FrameReadyCB cb) {

media/gpu/v4l2/v4l2_image_processor.h

@@ -28,7 +28,7 @@ namespace media {
 // hardware accelerators (see V4L2VideoDecodeAccelerator) for more details.
 class MEDIA_GPU_EXPORT V4L2ImageProcessor : public ImageProcessor {
  public:
-  explicit V4L2ImageProcessor(const scoped_refptr<V4L2Device>& device,
+  explicit V4L2ImageProcessor(scoped_refptr<V4L2Device> device,
                               v4l2_memory input_memory_type,
                               v4l2_memory output_memory_type);
   ~V4L2ImageProcessor() override;
@@ -77,7 +77,7 @@ class MEDIA_GPU_EXPORT V4L2ImageProcessor : public ImageProcessor {
   // should pass non-empty |output_dmabuf_fds| and the processed frame will be
   // stored in those buffers. If the number of |output_dmabuf_fds| is not
   // expected, this function will return false.
-  bool Process(const scoped_refptr<VideoFrame>& frame,
+  bool Process(scoped_refptr<VideoFrame> frame,
                int output_buffer_index,
                std::vector<base::ScopedFD> output_dmabuf_fds,
                FrameReadyCB cb) override;