Add a command-line flag to set GPU rasterization multisampling.

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 1081 matching lines @@
       resource_(resource_provider->LockForWrite(resource_id)) {
 }
 
 ResourceProvider::ScopedWriteLockGr::~ScopedWriteLockGr() {
   DCHECK(thread_checker_.CalledOnValidThread());
   resource_provider_->UnlockForWrite(resource_);
 }
 
 SkSurface* ResourceProvider::ScopedWriteLockGr::GetSkSurface(
     bool use_distance_field_text,
-    bool can_use_lcd_text) {
+    bool can_use_lcd_text,
+    int msaa_sample_count) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(resource_->locked_for_write);
 
   bool create_surface =
       !resource_->sk_surface.get() ||
       !SurfaceHasMatchingProperties(use_distance_field_text, can_use_lcd_text);
   if (create_surface) {
     resource_provider_->LazyAllocate(resource_);
 
     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;
 
     class GrContext* gr_context = resource_provider_->GrContext();
     skia::RefPtr<GrTexture> gr_texture =
         skia::AdoptRef(gr_context->wrapBackendTexture(desc));
     if (!gr_texture)
       return nullptr;
     uint32_t flags = use_distance_field_text
                          ? SkSurfaceProps::kUseDistanceFieldFonts_Flag
                          : 0;
     // Use unknown pixel geometry to disable LCD text.
@@ skipping 1023 matching lines @@
   ContextProvider* context_provider = output_surface_->context_provider();
   return context_provider ? context_provider->ContextGL() : NULL;
 }
 
 class GrContext* ResourceProvider::GrContext() const {
   ContextProvider* context_provider = output_surface_->context_provider();
   return context_provider ? context_provider->GrContext() : NULL;
 }
 
 }  // namespace cc