Disable overscroll on Windows machines w/o touchscreen

content/browser/frame_host/navigation_controller_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/navigation_controller_impl.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
@@ skipping 23 matching lines @@
 #include "content/public/browser/render_widget_host.h"
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/storage_partition.h"
 #include "content/public/browser/user_metrics.h"
 #include "content/public/common/content_client.h"
 #include "content/public/common/content_constants.h"
 #include "net/base/escape.h"
 #include "net/base/mime_util.h"
 #include "net/base/net_util.h"
 #include "skia/ext/platform_canvas.h"
+#include "ui/base/touch/touch_device.h"
+#include "ui/base/touch/touch_enabled.h"
 #include "url/url_constants.h"
 
 namespace content {
 namespace {
 
 // Invoked when entries have been pruned, or removed. For example, if the
 // current entries are [google, digg, yahoo], with the current entry google,
 // and the user types in cnet, then digg and yahoo are pruned.
 void NotifyPrunedEntries(NavigationControllerImpl* nav_controller,
                          bool from_front,
@@ skipping 458 matching lines @@
 }
 
 int NavigationControllerImpl::GetIndexForOffset(int offset) const {
   return GetCurrentEntryIndex() + offset;
 }
 
 void NavigationControllerImpl::TakeScreenshot() {
   screenshot_manager_->TakeScreenshot();
 }
 
+bool NavigationControllerImpl::ShouldTakeScreenshotOnNavigation() {
+  if (!delegate_->CanOverscrollContent())
+    return false;
+
+  // Don't take screenshots on navigation on Windows and Unix 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 unnecessarily.
+#if defined(OS_BSD) || defined(OS_FREEBSD) || defined(OS_LINUX) \
+  || defined(OS_OPENBSD) || defined(OS_POSIX) || defined(OS_QNX) \
+  || defined(OS_WIN)
+  return ui::IsTouchDevicePresent() && ui::AreTouchEventsEnabled();
+#else
+  return true;
+#endif
+}
+
 void NavigationControllerImpl::SetScreenshotManager(
     NavigationEntryScreenshotManager* manager) {
   screenshot_manager_.reset(manager ? manager :
                             new NavigationEntryScreenshotManager(this));
 }
 
 bool NavigationControllerImpl::CanGoBack() const {
   return entries_.size() > 1 && GetCurrentEntryIndex() > 0;
 }
 
@@ skipping 1256 matching lines @@
     }
   }
 }
 
 void NavigationControllerImpl::SetGetTimestampCallbackForTest(
     const base::Callback<base::Time()>& get_timestamp_callback) {
   get_timestamp_callback_ = get_timestamp_callback;
 }
 
 }  // namespace content