Replace hide-scrollbars flag with a web setting.

content/renderer/render_view_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_view_impl.h"
 
 #include <algorithm>
 #include <cmath>
 #include <memory>
 
@@ skipping 986 matching lines @@
   // and support is compiled in.
   settings->setExperimentalWebGLEnabled(prefs.experimental_webgl_enabled);
 
   // Enable WebGL errors to the JS console if requested.
   settings->setWebGLErrorsToConsoleEnabled(
       prefs.webgl_errors_to_console_enabled);
 
   // Uses the mock theme engine for scrollbars.
   settings->setMockScrollbarsEnabled(prefs.mock_scrollbars_enabled);
 
+  settings->setHideScrollbars(prefs.hide_scrollbars);
+
   // Enable gpu-accelerated 2d canvas if requested on the command line.
   WebRuntimeFeatures::enableAccelerated2dCanvas(
       prefs.accelerated_2d_canvas_enabled);
 
   settings->setMinimumAccelerated2dCanvasSize(
       prefs.minimum_accelerated_2d_canvas_size);
 
   // Disable antialiasing for 2d canvas if requested on the command line.
   settings->setAntialiased2dCanvasEnabled(
       !prefs.antialiased_2d_canvas_disabled);
@@ skipping 2016 matching lines @@
         return render_frame->focused_pepper_plugin();
     }
     frame = frame->traverseNext(false);
   }
 
   return nullptr;
 }
 #endif
 
 }  // namespace content