Hide ash palette on lock screen, show it in guest mode.

TEST=manual
BUG=638994

Review-Url: https://codereview.chromium.org/2280293002
Cr-Commit-Position: refs/heads/master@{#415209}

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

@@ -231,6 +231,10 @@ void PaletteTray::SessionStateChanged(
   UpdateIconVisibility();
 }
 
+void PaletteTray::OnLockStateChanged(bool locked) {
+  UpdateIconVisibility();
+}
+
 void PaletteTray::ClickedOutsideBubble() {
   bubble_.reset();
 }

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

@@ -45,6 +45,9 @@ class ASH_EXPORT PaletteTray : public TrayBackgroundView,
   // SessionStateObserver:
   void SessionStateChanged(SessionStateDelegate::SessionState state) override;
 
+  // ShellObserver:
+  void OnLockStateChanged(bool locked) override;
+
   // TrayBackgroundView:
   void ClickedOutsideBubble() override;
   base::string16 GetAccessibleNameForTray() override;

chrome/browser/chromeos/login/chrome_restart_request.cc

@@ -179,6 +179,8 @@ void DeriveCommandLine(const GURL& start_url,
     app_list::switches::kEnableCenteredAppList,
     app_list::switches::kEnableSyncAppList,
     ash::switches::kAshEnableTouchView,
+    ash::switches::kAshEnablePalette,
+    ash::switches::kAshEnableExperimentalPaletteFeatures,
     ash::switches::kAshEnableUnifiedDesktop,
     ash::switches::kAshHostWindowBounds,
     ash::switches::kAshTouchHud,