Fix incorrect VideoFrame::row_bytes() for RGB. Add tests.

media/base/video_util.h

Index: media/base/video_util.h
diff --git a/media/base/video_util.h b/media/base/video_util.h
index 3d21c8c1e39707ee48f48ae6cca59b1ddd2b97c6..e22f77f09be28e56d2bfd9447768ba91268e90d4 100644
--- a/media/base/video_util.h
+++ b/media/base/video_util.h
@@ -16,11 +16,11 @@ class VideoFrame;
 // source and destinations dimensions.
 //
 // NOTE: rows is *not* the same as height!
-MEDIA_EXPORT void CopyYPlane(const uint8* source, int stride, int rows,
+MEDIA_EXPORT void CopyYPlane(const uint8* source, size_t stride, size_t rows,
                              VideoFrame* frame);
-MEDIA_EXPORT void CopyUPlane(const uint8* source, int stride, int rows,
+MEDIA_EXPORT void CopyUPlane(const uint8* source, size_t stride, size_t rows,
                              VideoFrame* frame);
-MEDIA_EXPORT void CopyVPlane(const uint8* source, int stride, int rows,
+MEDIA_EXPORT void CopyVPlane(const uint8* source, size_t stride, size_t rows,
                              VideoFrame* frame);
 
 // Fills |frame| containing YUV data to the given color values.