Enable smooth scrolling on mac

content/renderer/renderer_main.cc

Index: content/renderer/renderer_main.cc
diff --git a/content/renderer/renderer_main.cc b/content/renderer/renderer_main.cc
index 2c1937b863a4ead326ca5f3c2f4665212a772d1c..5f7550df606b4bc0443fefc56169deb766b62651 100644
--- a/content/renderer/renderer_main.cc
+++ b/content/renderer/renderer_main.cc
@@ -33,6 +33,7 @@
 #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
@@ -129,6 +130,10 @@ int RendererMain(const MainFunctionParams& parameters) {
 
 #if defined(OS_MACOSX)
   InstallFrameworkHacks();
+
+  base::ScopedSmoothScrollingDisabler disable_smooth_scrolling(
+      parsed_command_line.HasSwitch(
+          switches::kDisableMacSmoothScrollingForTesting));
 #endif  // OS_MACOSX
 
 #if defined(OS_CHROMEOS)