Handle UNPIN operation in ash.

ash/accelerators/accelerator_commands.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 "ash/accelerators/accelerator_commands.h"
 
 #include "ash/common/wm/mru_window_tracker.h"
 #include "ash/common/wm/window_state.h"
 #include "ash/common/wm/wm_event.h"
 #include "ash/common/wm_window.h"
@@ skipping 89 matching lines @@
     const std::vector<DisplayMode>& modes = display_info.display_modes();
     auto iter =
         std::find_if(modes.begin(), modes.end(),
                      [](const DisplayMode& mode) { return mode.native; });
     display_manager->SetDisplayMode(DisplayManager::kUnifiedDisplayId, *iter);
   } else {
     SetDisplayUIScale(display_manager->GetDisplayIdForUIScaling(), 1.0f);
   }
 }
 
+void Unpin() {
+  wm::WindowState* window_state = wm::GetActiveWindowState();

[oshima, 2016/06/18 09:48:22]

I think it's safer to get pinned window from ScreenPinningController.
It *should* be same, but active window can change even during pinned (system
modal, lock screen are example)

[hidehiko, 2016/06/18 10:02:23]

I see. Done.

+  if (window_state->IsPinned())
+    window_state->Restore();
+}
+
 }  // namespace accelerators
 }  // namespace ash