Revert of Remove the acclerated overflow scroll and fixed root background flags.

content/browser/android/content_startup_flags.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/android/content_startup_flags.h"
 
 #include "base/base_switches.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 34 matching lines @@
     RenderProcessHost::SetMaxRendererProcessCount(limit);
   }
 
   if (single_process || command_line_renderer_limit == 0) {
     // Need to ensure the command line flag is consistent as a lot of chrome
     // internal code checks this directly, but it wouldn't normally get set when
     // we are implementing an embedded WebView.
     parsed_command_line->AppendSwitch(switches::kSingleProcess);
   }
 
+  parsed_command_line->AppendSwitch(switches::kEnableAcceleratedOverflowScroll);
   parsed_command_line->AppendSwitch(switches::kEnableBeginFrameScheduling);
 
   parsed_command_line->AppendSwitch(switches::kEnablePinch);
   parsed_command_line->AppendSwitch(switches::kEnableOverlayFullscreenVideo);
   parsed_command_line->AppendSwitch(switches::kEnableOverlayScrollbar);
   parsed_command_line->AppendSwitch(switches::kEnableOverscrollNotifications);
 
   // Run the GPU service as a thread in the browser instead of as a
   // standalone process.
   parsed_command_line->AppendSwitch(switches::kInProcessGPU);
@@ skipping 18 matching lines @@
   }
 
   // Disable profiler timing by default.
   if (!parsed_command_line->HasSwitch(switches::kProfilerTiming)) {
     parsed_command_line->AppendSwitchASCII(
         switches::kProfilerTiming, switches::kProfilerTimingDisabledValue);
   }
 }
 
 }  // namespace content