Allow arc app to lock screen orientation in TouchView/Tablet mode

ash/display/screen_orientation_controller_chromeos.cc

 // Copyright 2014 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 "ash/display/screen_orientation_controller_chromeos.h"
 
 #include "ash/common/ash_switches.h"
 #include "ash/common/display/display_info.h"
 #include "ash/common/wm/maximize_mode/maximize_mode_controller.h"
 #include "ash/common/wm_shell.h"
@@ skipping 94 matching lines @@
 
 void ScreenOrientationController::UnlockOrientationForWindow(
     aura::Window* window) {
   locking_windows_.erase(window);
   if (locking_windows_.empty())
     Shell::GetInstance()->activation_client()->RemoveObserver(this);
   window->RemoveObserver(this);
   ApplyLockForActiveWindow();
 }
 
+void ScreenOrientationController::UnlockAll() {
+  for (auto pair : locking_windows_)
+    pair.first->RemoveObserver(this);
+  locking_windows_.clear();
+  Shell::GetInstance()->activation_client()->RemoveObserver(this);
+  SetRotationLocked(false);
+  if (user_rotation_ != current_rotation_)
+    SetDisplayRotation(user_rotation_, display::Display::ROTATION_SOURCE_USER);
+}
+
 bool ScreenOrientationController::ScreenOrientationProviderSupported() const {
   return WmShell::Get()
              ->maximize_mode_controller()
              ->IsMaximizeModeWindowManagerEnabled() &&
          !base::CommandLine::ForCurrentProcess()->HasSwitch(
              switches::kAshDisableScreenOrientationLock);
 }
 
 void ScreenOrientationController::SetRotationLocked(bool rotation_locked) {
   if (rotation_locked_ == rotation_locked)
@@ skipping 254 matching lines @@
   if (!display_manager->registered_internal_display_rotation_lock())
     return;
   SetDisplayRotation(display_manager->registered_internal_display_rotation(),
                      display::Display::ROTATION_SOURCE_ACCELEROMETER);
   SetRotationLocked(true);
 }
 
 void ScreenOrientationController::ApplyLockForActiveWindow() {
   aura::Window* active_window =
       Shell::GetInstance()->activation_client()->GetActiveWindow();
-  for (auto const& windows : locking_windows_) {
-    if (windows.first->TargetVisibility() &&
-        active_window->Contains(windows.first)) {
-      LockRotationToOrientation(windows.second);
-      return;
+  if (active_window) {
+    for (auto const& windows : locking_windows_) {
+      if (windows.first->TargetVisibility() &&
+          active_window->Contains(windows.first)) {
+        LockRotationToOrientation(windows.second);
+        return;
+      }
     }
   }
   SetRotationLocked(false);
 }
 
 bool ScreenOrientationController::IsRotationAllowedInLockedState(
     display::Display::Rotation rotation) {
   if (!rotation_locked_)
     return true;
 
@@ skipping 11 matching lines @@
 }
 
 bool ScreenOrientationController::CanRotateInLockedState() {
   return rotation_locked_orientation_ ==
              blink::WebScreenOrientationLockLandscape ||
          rotation_locked_orientation_ ==
              blink::WebScreenOrientationLockPortrait;
 }
 
 }  // namespace ash