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

ui/events/base_event_utils.cc

 // 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/events/base_event_utils.h"
 
 #include "base/atomic_sequence_num.h"
 #include "base/command_line.h"
 #include "base/logging.h"
+#include "ui/base/touch/touch_device.h"

[sadrul, 2015/11/17 22:32:05]

This is in the ui_base target, which depends on the events_base target, which
base_event_utils.cc belongs to. This introduces a dependency cycle, and we
cannot have it.

 #include "ui/events/event_constants.h"
 #include "ui/events/event_switches.h"
 
 namespace ui {
 
 namespace {
 
 #if defined(OS_CHROMEOS)
 // Determines whether touch events are enabled or disabled on ChromeOS only.
 bool touch_events_enabled = true;
 
 const int kSystemKeyModifierMask = EF_ALT_DOWN | EF_COMMAND_DOWN;
 #else
 const int kSystemKeyModifierMask = EF_ALT_DOWN;
+#endif  // defined(OS_CHROMEOS)
 
-// Retrieves the status of the touch screen events from the command line on Non-
-// ChromeOS platforms.
+// Retrieves the status of the touch screen events from the command line.
 bool ComputeTouchStatus() {
   const base::CommandLine& 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 ||
-      touch_enabled_switch == switches::kTouchEventsAuto) {
+      touch_enabled_switch == switches::kTouchEventsEnabled) {
     return true;
   }
 
-  if (touch_enabled_switch == switches::kTouchEventsDisabled)
-    return false;
+  if (touch_enabled_switch == switches::kTouchEventsAuto)
+    return IsTouchDevicePresent();
 
-  LOG(ERROR) << "Invalid --touch-events option: " << touch_enabled_switch;
+  if (touch_enabled_switch != switches::kTouchEventsDisabled)
+    LOG(ERROR) << "Invalid --touch-events option: " << touch_enabled_switch;
   return false;
 }
 
-#endif  // defined(OS_CHROMEOS)
-
 }  // namespace
 
 base::StaticAtomicSequenceNumber g_next_event_id;
 
 uint32 GetNextTouchEventId() {
   // Set the first touch event ID to 1 because we set id to 0 for other types
   // of events.
   uint32 id = g_next_event_id.GetNext();
   if (id == 0)
     id = g_next_event_id.GetNext();
@@ skipping 10 matching lines @@
 
 #if defined(OS_CHROMEOS)
 
 void SetTouchEventsEnabled(bool enabled) {
   touch_events_enabled = enabled;
 }
 
 #endif  // defined(OS_CHROMEOS)
 
 bool AreTouchEventsEnabled() {
+  static bool touch_status = ComputeTouchStatus();
+
 #if defined(OS_CHROMEOS)
-  return touch_events_enabled;
+  return touch_events_enabled && touch_status;
 #else
-  static bool touch_events_enabled = ComputeTouchStatus();
-  return touch_events_enabled;
+  return touch_status;
 #endif  // !defined(OS_CHROMEOS)
 }
 
 }  // namespace ui