overscroll: Disable overscroll by default.

content/browser/web_contents/navigation_controller_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/browser/web_contents/navigation_controller_impl.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/file_util.h"
 #include "base/logging.h"
@@ skipping 461 matching lines @@
     return NULL;
 
   return entries_[index].get();
 }
 
 int NavigationControllerImpl::GetIndexForOffset(int offset) const {
   return GetCurrentEntryIndex() + offset;
 }
 
 void NavigationControllerImpl::TakeScreenshot() {
-  static bool overscroll_enabled = !CommandLine::ForCurrentProcess()->
-      HasSwitch(switches::kDisableOverscrollHistoryNavigation);
+  static bool overscroll_enabled = CommandLine::ForCurrentProcess()->
+      HasSwitch(switches::kEnableOverscrollHistoryNavigation);
   if (!overscroll_enabled)
     return;
 
   NavigationEntryImpl* entry =
       NavigationEntryImpl::FromNavigationEntry(GetLastCommittedEntry());
   if (!entry)
     return;
 
   RenderViewHost* render_view_host = web_contents_->GetRenderViewHost();
   if (!static_cast<RenderViewHostImpl*>
@@ skipping 1285 matching lines @@
     const base::Callback<base::Time()>& get_timestamp_callback) {
   get_timestamp_callback_ = get_timestamp_callback;
 }
 
 void NavigationControllerImpl::SetTakeScreenshotCallbackForTest(
     const base::Callback<void(RenderViewHost*)>& take_screenshot_callback) {
   take_screenshot_callback_ = take_screenshot_callback;
 }
 
 }  // namespace content