Fix a regression in checking the status of the touch events.

ui/base/touch/touch_enabled.cc

Index: ui/base/touch/touch_enabled.cc
diff --git a/ui/base/touch/touch_enabled.cc b/ui/base/touch/touch_enabled.cc
new file mode 100644
index 0000000000000000000000000000000000000000..6791a2557699be88b3363cfa3e3ae3669ecfb112
--- /dev/null
+++ b/ui/base/touch/touch_enabled.cc
@@ -0,0 +1,51 @@
+// Copyright 2015 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 "ui/base/touch/touch_enabled.h"
+
+#include "base/command_line.h"
+#include "base/logging.h"
+#include "ui/base/touch/touch_device.h"
+#include "ui/base/ui_base_switches.h"
+#include "ui/events/base_event_utils.h"
+#include "ui/events/event_switches.h"
+
+namespace ui {
+
+namespace {
+
+bool ComputeTouchStatus() {
+  auto* command_line = base::CommandLine::ForCurrentProcess();
+  const std::string touch_enabled_switch =
+      command_line->HasSwitch(switches::kTouchEvents) ?
+          command_line->GetSwitchValueASCII(switches::kTouchEvents) :
+          switches::kTouchEventsAuto;
+
+  if (touch_enabled_switch.empty() ||
+      touch_enabled_switch == switches::kTouchEventsEnabled) {
+    return true;
+  }
+
+  if (touch_enabled_switch == switches::kTouchEventsAuto)
+    return IsTouchDevicePresent();
+
+  DLOG_IF(ERROR, touch_enabled_switch != switches::kTouchEventsDisabled) <<
+      "Invalid --touch-events option: " << touch_enabled_switch;
+  return false;
+}
+
+}  // namespace
+
+bool AreTouchEventsEnabled() {
+  static bool touch_status = ComputeTouchStatus();
+
+#if defined(OS_CHROMEOS) && defined(USE_X11)
+  return touch_status && GetTouchEventsCrOsX11MasterSwitch();

[sadrul, 2015/11/18 20:58:46]

On a chromeos device build (i.e. when USE_X11 is not defined), we are not
looking at the master switch ... which means the debug accelerators will not do
the right thing anymore?

[afakhry, 2015/11/18 21:03:13]

On non-X11 ChromeOS builds (i.e. Ozone builds) we are using a different approach
to toggle the touch device. Please take a look here:
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/chr...

[sadrul, 2015/11/18 21:14:30]

The various places that call AreTouchEventsEnabled() are going to get the wrong
value though, right? (e.g. new pages created after turning off the touchscreen
using the debug accelerator will still think that touch events are available)

[afakhry, 2015/11/18 21:33:04]

Valid point! Thanks. I now set the switch on ozone as well.

+#else
+  return touch_status;
+#endif  // !defined(OS_CHROMEOS) && defined(USE_X11)
+}
+
+}  // namespace ui
+