Add pref to enable/disable palette tray.

ash/common/system/chromeos/palette/palette_tray.cc

 // Copyright 2016 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/common/system/chromeos/palette/palette_tray.h"
 
-#include "ash/common/palette_delegate.h"
 #include "ash/common/shelf/shelf_constants.h"
 #include "ash/common/shelf/wm_shelf.h"
 #include "ash/common/shelf/wm_shelf_util.h"
 #include "ash/common/shell_window_ids.h"
 #include "ash/common/system/chromeos/palette/palette_tool_manager.h"
 #include "ash/common/system/chromeos/palette/palette_utils.h"
 #include "ash/common/system/tray/system_tray_delegate.h"
 #include "ash/common/system/tray/tray_bubble_wrapper.h"
 #include "ash/common/system/tray/tray_constants.h"
 #include "ash/common/system/tray/tray_popup_header_button.h"
@@ skipping 99 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(TitleView);
 };
 
 }  // namespace
 
 PaletteTray::PaletteTray(WmShelf* wm_shelf)
     : TrayBackgroundView(wm_shelf),
       palette_tool_manager_(new PaletteToolManager(this)),
       weak_factory_(this) {
+  // PaletteTray should only be instantiated if the palette feature is enabled.
+  DCHECK(IsPaletteFeatureEnabled());
+
   PaletteTool::RegisterToolInstances(palette_tool_manager_.get());
 
   SetContentsBackground();
 
   SetLayoutManager(new views::FillLayout());
   icon_ = new views::ImageView();
   UpdateTrayIcon();
 
   SetIconBorderForShelfAlignment();
   tray_container()->AddChildView(icon_);
 
   WmShell::Get()->AddShellObserver(this);
   WmShell::Get()->GetSessionStateDelegate()->AddSessionStateObserver(this);
   if (WmShell::Get()->palette_delegate()) {
     WmShell::Get()->palette_delegate()->SetStylusStateChangedCallback(
         base::Bind(&PaletteTray::OnStylusStateChanged,
                    weak_factory_.GetWeakPtr()));
   }
 
-  UpdateIconVisibility();
+  // OnPaletteEnabledPrefChanged will get called with the initial pref value,
+  // which will take care of showing the palette.
+  palette_enabled_subscription_ =
+      WmShell::Get()->palette_delegate()->AddPaletteEnableListener(
+          base::Bind(&PaletteTray::OnPaletteEnabledPrefChanged,
+                     weak_factory_.GetWeakPtr()));
 }
 
 PaletteTray::~PaletteTray() {
   if (bubble_)
     bubble_->bubble_view()->reset_delegate();
 
   WmShell::Get()->RemoveShellObserver(this);
   WmShell::Get()->GetSessionStateDelegate()->RemoveSessionStateObserver(this);
 }
 
@@ skipping 169 matching lines @@
 void PaletteTray::OnStylusStateChanged(ui::StylusState stylus_state) {
   if (!WmShell::Get()->palette_delegate()->ShouldAutoOpenPalette())
     return;
 
   if (stylus_state == ui::StylusState::REMOVED && !bubble_)
     OpenBubble();
   else if (stylus_state == ui::StylusState::INSERTED && bubble_)
     bubble_.reset();
 }
 
+void PaletteTray::OnPaletteEnabledPrefChanged(bool enabled) {
+  if (!enabled)
+    SetVisible(false);
+  else
+    UpdateIconVisibility();
+}
+
 void PaletteTray::UpdateIconVisibility() {
-  if (!IsPaletteEnabled())
-    return;
-
   SessionStateDelegate* session_state_delegate =
       WmShell::Get()->GetSessionStateDelegate();
 
   SetVisible(!session_state_delegate->IsScreenLocked() &&
              session_state_delegate->GetSessionState() ==
                  SessionStateDelegate::SESSION_STATE_ACTIVE &&
              WmShell::Get()->system_tray_delegate()->GetUserLoginStatus() !=
                  LoginStatus::KIOSK_APP);
 }
 
 }  // namespace ash