Skip drawing unsupported layers in forced software mode

cc/layers/append_quads_data.h

 // Copyright 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.
 
 #ifndef CC_LAYERS_APPEND_QUADS_DATA_H_
 #define CC_LAYERS_APPEND_QUADS_DATA_H_
 
 #include "base/basictypes.h"
 #include "cc/quads/render_pass.h"
 
 namespace cc {
 
 struct AppendQuadsData {
   AppendQuadsData()
-      : allow_tile_draw_quads(true),
-        had_occlusion_from_outside_target_surface(false),
+      : had_occlusion_from_outside_target_surface(false),
         had_incomplete_tile(false),
         num_missing_tiles(0),
         render_pass_id(0, 0) {}
 
   explicit AppendQuadsData(RenderPass::Id render_pass_id)
-      : allow_tile_draw_quads(true),
-        had_occlusion_from_outside_target_surface(false),
+      : had_occlusion_from_outside_target_surface(false),
         had_incomplete_tile(false),
         num_missing_tiles(0),
         render_pass_id(render_pass_id) {}
 
-  // Set by LayerTreeHostImpl.
-  bool allow_tile_draw_quads;
   // Set by the QuadCuller.
   bool had_occlusion_from_outside_target_surface;
   // Set by the layer appending quads.
   bool had_incomplete_tile;
   // Set by the layer appending quads.
   int64 num_missing_tiles;
   // Given to the layer appending quads.
   const RenderPass::Id render_pass_id;
 };
 
 }  // namespace cc
 #endif  // CC_LAYERS_APPEND_QUADS_DATA_H_