Fix formatting/style nits in command buffer code

Bug: none
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: I2a125825faf342373faa4b957788c6e90692a71b
Reviewed-on: https://chromium-review.googlesource.com/996801Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548310}

gpu/command_buffer/service/framebuffer_manager.cc

@@ -872,8 +872,8 @@ bool Framebuffer::HasAlphaMRT() const {
       const Attachment* attachment = GetAttachment(draw_buffers_[i]);
       if (!attachment)
         continue;
-      if ((GLES2Util::GetChannelsForFormat(
-               attachment->internal_format()) & 0x0008) != 0)
+      if ((GLES2Util::GetChannelsForFormat(attachment->internal_format()) &
+           GLES2Util::kAlpha) != 0)
         return true;
     }
   }