compositor: Enable partial raster by default.

content/browser/gpu/compositor_util.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/browser/gpu/compositor_util.h"
 
 #include <stddef.h>
 
 #include "base/command_line.h"
 #include "base/logging.h"
@@ skipping 208 matching lines @@
 #else
   return command_line.HasSwitch(switches::kEnableZeroCopy);
 #endif
 }
 
 bool IsPartialRasterEnabled() {
   // Zero copy currently doesn't take advantage of partial raster.
   if (IsZeroCopyUploadEnabled())
     return false;
   const auto& command_line = *base::CommandLine::ForCurrentProcess();
-  return command_line.HasSwitch(switches::kEnablePartialRaster);
+  return !command_line.HasSwitch(switches::kDisablePartialRaster);
 }
 
 bool IsGpuMemoryBufferCompositorResourcesEnabled() {
   const base::CommandLine& command_line =
       *base::CommandLine::ForCurrentProcess();
   if (command_line.HasSwitch(
           switches::kEnableGpuMemoryBufferCompositorResources)) {
     return true;
   }
   if (command_line.HasSwitch(
@@ skipping 165 matching lines @@
     }
   }
   return problem_list;
 }
 
 std::vector<std::string> GetDriverBugWorkarounds() {
   return GpuDataManagerImpl::GetInstance()->GetDriverBugWorkarounds();
 }
 
 }  // namespace content