cc: Use ResourceUtil::UncheckedWidthInBytes() in CopyOnWorkerThread().

cc/raster/one_copy_tile_task_worker_pool.cc

Index: cc/raster/one_copy_tile_task_worker_pool.cc
diff --git a/cc/raster/one_copy_tile_task_worker_pool.cc b/cc/raster/one_copy_tile_task_worker_pool.cc
index a07ea8965f4ca5c92c6d807d7a0c706f64b0539a..d24624cfc802c64682fe0903986d2267bd835e74 100644
--- a/cc/raster/one_copy_tile_task_worker_pool.cc
+++ b/cc/raster/one_copy_tile_task_worker_pool.cc
@@ -325,8 +325,8 @@ void OneCopyTileTaskWorkerPool::CopyOnWorkerThread(
       gl->CompressedCopyTextureCHROMIUM(staging_buffer->texture_id,
                                         resource_lock->texture_id());
     } else {
-      int bytes_per_row =
-          (BitsPerPixel(resource->format()) * resource->size().width()) / 8;
+      int bytes_per_row = ResourceUtil::UncheckedWidthInBytes<int>(

[danakj, 2016/04/13 18:38:59]

If it can overflow/underflow then you want to use Checked math. Unchecked is for
when you can prove to yourself that it can't.

[reveman, 2016/04/17 20:22:59]

I don't think we want unnecessary conditionals to be executed here to check if
this overflow/underflow unless we're in a debug build. There's no reason this
should overflow/underflow unless there's a bug in our code. Unchecked seems
appropriate.

[danakj, 2016/04/18 19:47:53]

ok sg thanks, just wanted to be sure. LGTM then

+          resource->size().width(), resource->format());
       int chunk_size_in_rows =
           std::max(1, max_bytes_per_copy_operation_ / bytes_per_row);
       // Align chunk size to 4. Required to support compressed texture formats.