Disable overscroll on Windows machines w/o touchscreen

content/browser/frame_host/navigator_impl.cc

 // Copyright 2013 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/frame_host/navigator_impl.h"
 
 #include "base/command_line.h"
 #include "base/time/time.h"
 #include "content/browser/frame_host/frame_tree.h"
 #include "content/browser/frame_host/frame_tree_node.h"
@@ skipping 441 matching lines @@
   }
 
   if (ui::PageTransitionIsMainFrame(params.transition)) {
     if (delegate_) {
       // When overscroll navigation gesture is enabled, a screenshot of the page
       // in its current state is taken so that it can be used during the
       // nav-gesture. It is necessary to take the screenshot here, before
       // calling RenderFrameHostManager::DidNavigateMainFrame, because that can
       // change WebContents::GetRenderViewHost to return the new host, instead
       // of the one that may have just been swapped out.
-      if (delegate_->CanOverscrollContent()) {
+      if (controller_->ShouldTakeScreenshotOnNavigation()) {

[sadrul, 2014/09/29 20:39:24]

Can we change the Browser::CanOverscrollContent() override instead?

[mfomitchev, 2014/09/29 20:41:39]

This was my first intention, but then I thought it might be better to leave the
overscroll gesture enabled and just disable the screenshot taking - please see
my first comment on the review.

         // Don't take screenshots if we are staying on the same page. We want
         // in-page navigations to be super fast, and taking a screenshot
         // currently blocks GPU for a longer time than we are willing to
         // tolerate in this use case.
         if (!params.was_within_same_page)
           controller_->TakeScreenshot();
       }
 
       // Run tasks that must execute just before the commit.
       bool is_navigation_within_page = controller_->IsURLInPageNavigation(
@@ skipping 209 matching lines @@
           controller_->GetBrowserContext(), url);
   if ((enabled_bindings & BINDINGS_POLICY_WEB_UI) &&
       !is_allowed_in_web_ui_renderer) {
     // Log the URL to help us diagnose any future failures of this CHECK.
     GetContentClient()->SetActiveURL(url);
     CHECK(0);
   }
 }
 
 }  // namespace content