Reland: Refactor Vaapi video decoder/encoder in preparation of Freon support

ui/gl/gl_image_glx.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 extern "C" {
 #include <X11/Xlib.h>
 }
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 43 matching lines @@
     default:
       NOTREACHED();
       return 0;
   }
 }
 
 unsigned PixmapDepth(unsigned internalformat) {
   switch (internalformat) {
     case GL_RGBA:
       return 32u;
+    case GL_RGB:
+      return 24u;
     default:
       NOTREACHED();
       return 0u;
   }
 }
 
 bool ActualPixmapGeometry(XID pixmap, gfx::Size* size, unsigned* depth) {
   XID root_return;
   int x_return;
   int y_return;
@@ skipping 126 matching lines @@
 
 bool GLImageGLX::ScheduleOverlayPlane(gfx::AcceleratedWidget widget,
                                       int z_order,
                                       OverlayTransform transform,
                                       const Rect& bounds_rect,
                                       const RectF& crop_rect) {
   return false;
 }
 
 }  // namespace gfx