Enable smooth scrolling on mac

content/renderer/renderer_main.cc

 // Copyright (c) 2011 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 "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/i18n/rtl.h"
 #include "base/mac/scoped_nsautorelease_pool.h"
 #include "base/memory/ref_counted.h"
 #include "base/metrics/field_trial.h"
@@ skipping 15 matching lines @@
 #include "content/renderer/render_thread.h"
 #include "content/renderer/renderer_main_platform_delegate.h"
 #include "ui/base/ui_base_switches.h"
 
 #if defined(OS_MACOSX)
 #include <Carbon/Carbon.h>
 #include <signal.h>
 #include <unistd.h>
 
 #include "base/mac/mac_util.h"
+#include "base/mac/scoped_smooth_scrolling_disabler_mac.h"
 #include "third_party/mach_override/mach_override.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebView.h"
 #endif  // OS_MACOSX
 
 #if defined(OS_MACOSX)
 namespace {
 
 CFArrayRef ChromeTISCreateInputSourceList(
    CFDictionaryRef properties,
    Boolean includeAllInstalled) {
@@ skipping 76 matching lines @@
 
 // mainline routine for running as the Renderer process
 int RendererMain(const MainFunctionParams& parameters) {
   TRACE_EVENT_BEGIN_ETW("RendererMain", 0, "");
 
   const CommandLine& parsed_command_line = parameters.command_line_;
   base::mac::ScopedNSAutoreleasePool* pool = parameters.autorelease_pool_;
 
 #if defined(OS_MACOSX)
   InstallFrameworkHacks();
+
+  base::ScopedSmoothScrollingDisabler disable_smooth_scrolling(
+      parsed_command_line.HasSwitch(
+          switches::kDisableMacSmoothScrollingForTesting));
 #endif  // OS_MACOSX
 
 #if defined(OS_CHROMEOS)
   // As Zygote process starts up earlier than browser process gets its own
   // locale (at login time for Chrome OS), we have to set the ICU default
   // locale for renderer process here.
   // ICU locale will be used for fallback font selection etc.
   if (parsed_command_line.HasSwitch(switches::kLang)) {
     const std::string locale =
         parsed_command_line.GetSwitchValueASCII(switches::kLang);
@@ skipping 84 matching lines @@
         pool->Recycle();
       TRACE_EVENT_BEGIN_ETW("RendererMain.START_MSG_LOOP", 0, 0);
       MessageLoop::current()->Run();
       TRACE_EVENT_END_ETW("RendererMain.START_MSG_LOOP", 0, 0);
     }
   }
   platform.PlatformUninitialize();
   TRACE_EVENT_END_ETW("RendererMain", 0, "");
   return 0;
 }