Fix missing parens in ConvertVideoFrameToRGBPixelsTask

BUG=1016035
R=dalecurtis

Change-Id: I3c12fe8c339ab326d910699739e289b5e9aaa343
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1872724
Auto-Submit: Thomas Anderson <thomasanderson@chromium.org>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#708399}

media/renderers/paint_canvas_video_renderer.cc

@@ -433,7 +433,7 @@ void ConvertVideoFrameToRGBPixelsTask(const VideoFrame* video_frame,
       const uint8_t* data = video_frame->visible_data(plane);
       int rows = video_frame->rows(plane);
       meta.data =
-          data + meta.stride * chunk_start * rows_per_chunk * rows / height;
+          data + meta.stride * (chunk_start * rows_per_chunk * rows / height);
     }
   }