media/gpu/v4l2: pass format to AllocatedSizeFromV4L2Format by reference

AllocatedSizeFromV4L2Format() returns the calculated size of a buffer,
being given its V4L2 format. This method does not modify the format
whatsoever ; thus, pass it as const reference in order to avoid an
unneeded copy.

Bug: None
Test: video_decode_accelerator_tests passes on Kevin.

Change-Id: Ifd0bf98022efe44a6b72f6c684a452c969add83d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1871490
Auto-Submit: Alexandre Courbot <acourbot@chromium.org>
Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Commit-Queue: Hirokazu Honda <hiroh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#708069}

media/gpu/v4l2/v4l2_device.cc

@@ -1356,7 +1356,8 @@ int32_t V4L2Device::H264LevelIdcToV4L2H264Level(uint8_t level_idc) {
 }
 
 // static
-gfx::Size V4L2Device::AllocatedSizeFromV4L2Format(struct v4l2_format format) {
+gfx::Size V4L2Device::AllocatedSizeFromV4L2Format(
+    const struct v4l2_format& format) {
   gfx::Size coded_size;
   gfx::Size visible_size;
   VideoPixelFormat frame_format = PIXEL_FORMAT_UNKNOWN;

media/gpu/v4l2/v4l2_device.h

@@ -390,7 +390,8 @@ class MEDIA_GPU_EXPORT V4L2Device
       bool is_encoder);
   static uint32_t V4L2PixFmtToDrmFormat(uint32_t format);
   // Calculates the largest plane's allocation size requested by a V4L2 device.
-  static gfx::Size AllocatedSizeFromV4L2Format(struct v4l2_format format);
+  static gfx::Size AllocatedSizeFromV4L2Format(
+      const struct v4l2_format& format);
 
   // Convert required H264 profile and level to V4L2 enums.
   static int32_t VideoCodecProfileToV4L2H264Profile(VideoCodecProfile profile);