Disable overscroll on Windows machines w/o touchscreen

chrome/browser/ui/browser.cc

 // Copyright 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 "chrome/browser/ui/browser.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include <shellapi.h>
 #endif  // defined(OS_WIN)
@@ skipping 173 matching lines @@
 #include "extensions/browser/extension_system.h"
 #include "extensions/common/constants.h"
 #include "extensions/common/extension.h"
 #include "extensions/common/manifest_handlers/background_info.h"
 #include "net/base/filename_util.h"
 #include "net/base/registry_controlled_domains/registry_controlled_domain.h"
 #include "net/cookies/cookie_monster.h"
 #include "net/url_request/url_request_context.h"
 #include "third_party/WebKit/public/web/WebWindowFeatures.h"
 #include "ui/base/l10n/l10n_util.h"
+#include "ui/base/touch/touch_device.h"

[sadrul, 2014/09/30 16:32:15]

Add this include below for OS_WIN in line ~200?

[mfomitchev, 2014/09/30 18:30:33]

Done.

 #include "ui/base/window_open_disposition.h"
 #include "ui/gfx/point.h"
 #include "ui/shell_dialogs/selected_file_info.h"
 
 #if defined(OS_WIN)
 #include "base/win/metro.h"
 #include "chrome/browser/ssl/ssl_error_info.h"
 #include "chrome/browser/task_manager/task_manager.h"
 #include "chrome/browser/ui/view_ids.h"
 #include "components/autofill/core/browser/autofill_ie_toolbar_import_win.h"
@@ skipping 916 matching lines @@
   //       still present.
   base::MessageLoop::current()->PostTask(
       FROM_HERE, base::Bind(&Browser::CloseFrame, weak_factory_.GetWeakPtr()));
 
   // Instant may have visible WebContents that need to be detached before the
   // window system closes.
   instant_controller_.reset();
 }
 
 bool Browser::CanOverscrollContent() const {
-#if defined(USE_AURA)
+#if defined(USE_AURA) && defined(OS_WIN)
+  // Don't enable overscroll on Windows machines unless they have a touch
+  // screen as these machines typically don't have a touchpad capable of
+  // horizontal scrolling. We are purposefully biased towards "no" here,
+  // so that we don't waste resources capturing screenshots for horizontal
+  // overscroll navigation unnecessarily.
+  bool allowOverscroll = ui::IsTouchDevicePresent();

[sadrul, 2014/09/30 16:32:15]

allow_overscroll

Also, AURA is always turned on for Windows, so just

#if defined(OS_WIN)
..
#elif defined(USE_AURA)
..
#else
..
#endif

or

#if defined(USE_AURA)
#if defined(OS_WIN)
...
#else
...
#endif
...
#endif

[mfomitchev, 2014/09/30 18:30:33]

Done.

+#elif defined(USE_AURA)
+  bool allowOverscroll = true;
+#else
+  bool allowOverscroll = false;
+#endif
+
+  if (!allowOverscroll)
+    return false;
+
   const std::string value = CommandLine::ForCurrentProcess()->
       GetSwitchValueASCII(switches::kOverscrollHistoryNavigation);
   bool overscroll_enabled = value != "0";
   if (!overscroll_enabled)
     return false;
   if (is_app() || is_devtools() || !is_type_tabbed())
     return false;
 
   // The detached bookmark bar has appearance of floating above the
   // web-contents. This does not play nicely with overscroll navigation
   // gestures. So disable overscroll navigation when the bookmark bar is in the
   // detached state and the overscroll effect moves the layers.
   if (value == "1" && bookmark_bar_state_ == BookmarkBar::DETACHED)
     return false;
   return true;
-#else
-  return false;
-#endif
 }
 
 bool Browser::ShouldPreserveAbortedURLs(WebContents* source) {
   // Allow failed URLs to stick around in the omnibox on the NTP, but not when
   // other pages have committed.
   Profile* profile = Profile::FromBrowserContext(source->GetBrowserContext());
   if (!profile || !source->GetController().GetLastCommittedEntry())
     return false;
   GURL committed_url(source->GetController().GetLastCommittedEntry()->GetURL());
   return chrome::IsNTPURL(committed_url, profile);
@@ skipping 1317 matching lines @@
   if (contents && !allow_js_access) {
     contents->web_contents()->GetController().LoadURL(
         target_url,
         content::Referrer(),
         ui::PAGE_TRANSITION_LINK,
         std::string());  // No extra headers.
   }
 
   return contents != NULL;
 }