Replaced is_null() with is_valid in SurfaceId and related classes.

cc/layers/surface_layer_impl.cc

 // Copyright 2014 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.
 
 #include "cc/layers/surface_layer_impl.h"
 
 #include <stdint.h>
 
 #include "base/trace_event/trace_event_argument.h"
 #include "cc/debug/debug_colors.h"
@@ skipping 52 matching lines @@
 }
 
 void SurfaceLayerImpl::AppendQuads(RenderPass* render_pass,
                                    AppendQuadsData* append_quads_data) {
   AppendRainbowDebugBorder(render_pass);
 
   SharedQuadState* shared_quad_state =
       render_pass->CreateAndAppendSharedQuadState();
   PopulateScaledSharedQuadState(shared_quad_state, surface_scale_);
 
-  if (surface_id_.is_null())
+  if (!surface_id_.is_valid())
     return;
 
   gfx::Rect quad_rect(surface_size_);
   gfx::Rect visible_quad_rect =
       draw_properties().occlusion_in_content_space.GetUnoccludedContentRect(
           quad_rect);
   if (visible_quad_rect.IsEmpty())
     return;
   SurfaceDrawQuad* quad =
       render_pass->CreateAndAppendDrawQuad<SurfaceDrawQuad>();
@@ skipping 96 matching lines @@
 void SurfaceLayerImpl::AsValueInto(base::trace_event::TracedValue* dict) const {
   LayerImpl::AsValueInto(dict);
   dict->SetString("surface_id", surface_id_.ToString());
 }
 
 const char* SurfaceLayerImpl::LayerTypeAsString() const {
   return "cc::SurfaceLayerImpl";
 }
 
 }  // namespace cc