Add WM_EVENT_TRUSTED_PIN and WINDOW_STATE_TYPE_TRUSTED_PINNED to Ash.

ash/accelerators/accelerator_controller_delegate_aura.cc

Index: ash/accelerators/accelerator_controller_delegate_aura.cc
diff --git a/ash/accelerators/accelerator_controller_delegate_aura.cc b/ash/accelerators/accelerator_controller_delegate_aura.cc
index 654edd57b44a4a8ebadda05b631ca00f2ec11d44..0a9c88f5fcd39aa23f6d627933ccf8df6181f7fa 100644
--- a/ash/accelerators/accelerator_controller_delegate_aura.cc
+++ b/ash/accelerators/accelerator_controller_delegate_aura.cc
@@ -314,8 +314,11 @@ void HandleToggleDesktopBackgroundMode() {
 }
 
 bool CanHandleUnpin() {
+  // Returns true only for WINDOW_STATE_TYPE_PINNED.
+  // WINDOW_STATE_TYPE_TRUSTED_PINNED does not accept user's unpin operation.
   wm::WindowState* window_state = wm::GetActiveWindowState();
-  return window_state && window_state->IsPinned();
+  return window_state &&
+         window_state->GetStateType() == wm::WINDOW_STATE_TYPE_PINNED;
 }
 
 #if defined(OS_CHROMEOS)