Chromium side for using overlay scrollbars on Aura or Linux.

content/browser/renderer_host/render_process_host_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.
 
 // Represents the browser side of the browser <--> renderer communication
 // channel. There will be one RenderProcessHost per renderer process.
 
 #include "content/browser/renderer_host/render_process_host_impl.h"
 
 #include <algorithm>
@@ skipping 914 matching lines @@
     switches::kDisableLegacyEncryptedMedia,
     switches::kOverrideEncryptedMediaCanPlayType,
     switches::kEnableExperimentalWebPlatformFeatures,
     switches::kEnableFixedLayout,
     switches::kEnableDeferredImageDecoding,
     switches::kEnableGPUServiceLogging,
     switches::kEnableGPUClientLogging,
     switches::kEnableGpuClientTracing,
     switches::kEnableGpuBenchmarking,
     switches::kEnableMemoryBenchmarking,
+    switches::kEnableOverlayScrollbars,
     switches::kEnableSkiaBenchmarking,
     switches::kEnableLogging,
     switches::kEnableSpeechSynthesis,
     switches::kEnableTouchDragDrop,
     switches::kEnableTouchEditing,
 #if defined(ENABLE_WEBRTC)
     switches::kEnableWebRtcAecRecordings,
     switches::kEnableWebRtcTcpServerSocket,
     switches::kEnableWebRtcHWDecoding,
 #endif
@@ skipping 859 matching lines @@
     // Skip widgets in other processes.
     if (widgets[i]->GetProcess()->GetID() != GetID())
       continue;
 
     RenderViewHost* rvh = RenderViewHost::From(widgets[i]);
     rvh->UpdateWebkitPreferences(rvh->GetWebkitPreferences());
   }
 }
 
 }  // namespace content