Add pref to enable/disable palette tray.

chrome/browser/ui/ash/palette_delegate_chromeos.h

Index: chrome/browser/ui/ash/palette_delegate_chromeos.h
diff --git a/chrome/browser/ui/ash/palette_delegate_chromeos.h b/chrome/browser/ui/ash/palette_delegate_chromeos.h
index 78cc1b718a5c071802e5eb1dd961f3f801c66205..f5b216a155f7b0a05843d495224646e9fbca720e 100644
--- a/chrome/browser/ui/ash/palette_delegate_chromeos.h
+++ b/chrome/browser/ui/ash/palette_delegate_chromeos.h
@@ -8,22 +8,36 @@
 #include <string>
 
 #include "ash/common/palette_delegate.h"
-#include "base/compiler_specific.h"
+#include "ash/common/session/session_state_observer.h"
+#include "base/callback_list.h"
 #include "base/macros.h"
 #include "base/values.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
 #include "ui/events/devices/input_device_event_observer.h"
 
+class PrefChangeRegistrar;
+class Profile;
+
+namespace ash {
+class ScopedSessionStateObserver;
+}
+
 namespace chromeos {
 
 // A class which allows the Ash palette to perform chrome actions.
 class PaletteDelegateChromeOS : public ash::PaletteDelegate,
-                                public ui::InputDeviceEventObserver {
+                                public ui::InputDeviceEventObserver,
+                                public ash::SessionStateObserver,
+                                public content::NotificationObserver {
  public:
   PaletteDelegateChromeOS();
   ~PaletteDelegateChromeOS() override;
 
  private:
   // ash::PaletteDelegate:
+  std::unique_ptr<EnableListenerSubscription> AddPaletteEnableListener(
+      const EnableListener& on_state_changed) override;
   void CreateNote() override;
   bool HasNoteApp() override;
   void SetPartialMagnifierState(bool enabled) override;
@@ -33,11 +47,31 @@ class PaletteDelegateChromeOS : public ash::PaletteDelegate,
   void TakeScreenshot() override;
   void TakePartialScreenshot() override;
 
+  // ash::SessionStateObserver:
+  void ActiveUserChanged(const AccountId& account_id) override;
+
+  // content::NotificationObserver:
+  void Observe(int type,
+               const content::NotificationSource& source,
+               const content::NotificationDetails& details) override;
+
   // ui::InputDeviceObserver:
   void OnStylusStateChanged(ui::StylusState state) override;
 
+  // Called when the palette enabled pref has changed.
+  void OnPaletteEnabledPrefChanged();
+
+  void SetProfile(Profile* profile);
+
+  base::CallbackList<void(bool)> palette_enabled_callback_list_;
   OnStylusStateChangedCallback on_stylus_state_changed_;
 
+  // Unowned pointer to the active profile.
+  Profile* profile_ = nullptr;
+  std::unique_ptr<PrefChangeRegistrar> pref_change_registrar_;
+  std::unique_ptr<ash::ScopedSessionStateObserver> session_state_observer_;
+  content::NotificationRegistrar registrar_;
+
   DISALLOW_COPY_AND_ASSIGN(PaletteDelegateChromeOS);
 };