compositor: Enable partial raster by default.

content/renderer/render_thread_impl.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.
 
 #include "content/renderer/render_thread_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <utility>
@@ skipping 728 matching lines @@
   layer_settings.use_compositor_animation_timelines =
       !command_line.HasSwitch(switches::kDisableCompositorAnimationTimelines);
   cc_blink::WebLayerImpl::SetLayerSettings(layer_settings);
   cc::SetClientNameForMetrics("Renderer");
 
   is_threaded_animation_enabled_ =
       !command_line.HasSwitch(cc::switches::kDisableThreadedAnimation);
 
   is_zero_copy_enabled_ = command_line.HasSwitch(switches::kEnableZeroCopy);
   is_partial_raster_enabled_ =
-      command_line.HasSwitch(switches::kEnablePartialRaster);
+      !command_line.HasSwitch(switches::kDisablePartialRaster);
   is_gpu_memory_buffer_compositor_resources_enabled_ = command_line.HasSwitch(
       switches::kEnableGpuMemoryBufferCompositorResources);
 
 #if defined(OS_MACOSX) && !defined(OS_IOS)
   is_elastic_overscroll_enabled_ = base::mac::IsOSLionOrLater();
   if (is_elastic_overscroll_enabled_) {
     base::ScopedCFTypeRef<CFStringRef> key(
         base::SysUTF8ToCFStringRef("NSScrollViewRubberbanding"));
     Boolean key_exists = false;
     Boolean value = CFPreferencesGetAppBooleanValue(
@@ skipping 1411 matching lines @@
 }
 
 void RenderThreadImpl::PendingRenderFrameConnect::OnConnectionError() {
   size_t erased =
       RenderThreadImpl::current()->pending_render_frame_connects_.erase(
           routing_id_);
   DCHECK_EQ(1u, erased);
 }
 
 }  // namespace content