cc: Add null checks for GrContext created by ContextProviderCommandBuffer.

cc/resources/resource_provider.cc

 // 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.
 
 #include "cc/resources/resource_provider.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/containers/hash_tables.h"
@@ skipping 1117 matching lines @@
   GrBackendTextureDesc desc;
   desc.fFlags = kRenderTarget_GrBackendTextureFlag;
   desc.fWidth = resource_->size.width();
   desc.fHeight = resource_->size.height();
   desc.fConfig = ToGrPixelConfig(resource_->format);
   desc.fOrigin = kTopLeft_GrSurfaceOrigin;
   desc.fTextureHandle = resource_->gl_id;
   desc.fSampleCnt = msaa_sample_count;
 
   bool use_worker_context = true;
+  skia::RefPtr<GrTexture> gr_texture;
   class GrContext* gr_context =
       resource_provider_->GrContext(use_worker_context);
-  skia::RefPtr<GrTexture> gr_texture =
-      skia::AdoptRef(gr_context->textureProvider()->wrapBackendTexture(desc));
+  if (gr_context)
+    gr_texture =
+        skia::AdoptRef(gr_context->textureProvider()->wrapBackendTexture(desc));
   if (gr_texture) {
     uint32_t flags = use_distance_field_text
                          ? SkSurfaceProps::kUseDistanceFieldFonts_Flag
                          : 0;
     // Use unknown pixel geometry to disable LCD text.
     SkSurfaceProps surface_props(flags, kUnknown_SkPixelGeometry);
     if (can_use_lcd_text) {
       // LegacyFontHost will get LCD text and skia figures out what type to use.
       surface_props =
           SkSurfaceProps(flags, SkSurfaceProps::kLegacyFontHost_InitType);
@@ skipping 904 matching lines @@
 }
 
 class GrContext* ResourceProvider::GrContext(bool worker_context) const {
   ContextProvider* context_provider =
       worker_context ? output_surface_->worker_context_provider()
                      : output_surface_->context_provider();
   return context_provider ? context_provider->GrContext() : NULL;
 }
 
 }  // namespace cc