Cancel partial screenshot UI when lock happens.

ash/wm/power_button_controller.h

Index: ash/wm/power_button_controller.h
diff --git a/ash/wm/power_button_controller.h b/ash/wm/power_button_controller.h
index 19f26fe5f70416ad7dcda2c9c2b3043aac0c833f..8ed9d51bd372b77d0c0d5daf0b1a3352f0baaf38 100644
--- a/ash/wm/power_button_controller.h
+++ b/ash/wm/power_button_controller.h
@@ -7,6 +7,8 @@
 #pragma once
 
 #include "ash/ash_export.h"
+#include "ash/shell.h"
+#include "ash/shell_observer.h"
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/time.h"
@@ -38,7 +40,8 @@ class ASH_EXPORT PowerButtonControllerDelegate {
 
 // Displays onscreen animations and locks or suspends the system in response to
 // the power button being pressed or released.
-class ASH_EXPORT PowerButtonController : public aura::RootWindowObserver {
+class ASH_EXPORT PowerButtonController : public aura::RootWindowObserver,
+                                         public ShellObserver {
  public:
   // Animations that can be applied to groups of containers.
   // Exposed here for TestApi::ContainerGroupIsAnimated().
@@ -135,16 +138,6 @@ class ASH_EXPORT PowerButtonController : public aura::RootWindowObserver {
     has_legacy_power_button_ = legacy;
   }
 
-  // Called when the user logs in.
-  void OnLoginStateChange(bool logged_in, bool is_guest);
-
-  // Called when the application is exiting.
-  void OnExit();
-
-  // Called when the screen is locked (after the lock window is visible) or
-  // unlocked.
-  void OnLockStateChange(bool locked);
-
   // Called when Chrome gets a request to display the lock screen.
   void OnStartingLock();
 
@@ -159,6 +152,11 @@ class ASH_EXPORT PowerButtonController : public aura::RootWindowObserver {
   virtual void OnRootWindowResized(const aura::RootWindow* root,
                                    const gfx::Size& old_size) OVERRIDE;
 
+  // ShellObserver overrides:
+  virtual void OnLoginStateChanged(Shell::LoginStatus status) OVERRIDE;
+  virtual void OnAppTerminating() OVERRIDE;
+  virtual void OnLockStateChanged(bool locked) OVERRIDE;
+
  private:
   bool logged_in_as_non_guest() const { return logged_in_ && !is_guest_; }