Add pref to enable/disable palette tray.

chrome/browser/ui/ash/palette_delegate_chromeos.cc

Index: chrome/browser/ui/ash/palette_delegate_chromeos.cc
diff --git a/chrome/browser/ui/ash/palette_delegate_chromeos.cc b/chrome/browser/ui/ash/palette_delegate_chromeos.cc
index 6bc49908f8b0851d779590bbe12861f1806b216b..3192f8b4bfe9ba1cef05121b3f5c968977d1497f 100644
--- a/chrome/browser/ui/ash/palette_delegate_chromeos.cc
+++ b/chrome/browser/ui/ash/palette_delegate_chromeos.cc
@@ -9,22 +9,27 @@
 #include "ash/screenshot_delegate.h"
 #include "ash/shell.h"
 #include "ash/utility/screenshot_controller.h"
+#include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/chromeos/note_taking_app_utils.h"
+#include "chrome/browser/chromeos/profiles/profile_helper.h"
+#include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/common/pref_names.h"
+#include "components/prefs/pref_change_registrar.h"
 #include "components/prefs/pref_service.h"
+#include "components/user_manager/user_manager.h"
+#include "content/public/browser/notification_service.h"
+#include "content/public/browser/notification_source.h"
 #include "ui/events/devices/input_device_manager.h"
 
 namespace chromeos {
-namespace {
-
-Profile* GetProfile() {
-  return ProfileManager::GetActiveUserProfile();
-}
-
-}  // namespace
 
 PaletteDelegateChromeOS::PaletteDelegateChromeOS() {
+  registrar_.Add(this, chrome::NOTIFICATION_SESSION_STARTED,
+                 content::NotificationService::AllSources());
+  registrar_.Add(this, chrome::NOTIFICATION_PROFILE_DESTROYED,
+                 content::NotificationService::AllSources());
+
   ui::InputDeviceManager::GetInstance()->AddObserver(this);
 }
 
@@ -32,12 +37,83 @@ PaletteDelegateChromeOS::~PaletteDelegateChromeOS() {
   ui::InputDeviceManager::GetInstance()->RemoveObserver(this);
 }
 
+std::unique_ptr<PaletteDelegateChromeOS::EnableListenerSubscription>
+PaletteDelegateChromeOS::AddPaletteEnableListener(
+    const EnableListener& on_state_changed) {
+  auto subscription = palette_enabled_callback_list_.Add(on_state_changed);
+  OnPaletteEnabledPrefChanged();
+  return subscription;
+}
+
 void PaletteDelegateChromeOS::CreateNote() {
-  chromeos::LaunchNoteTakingAppForNewNote(GetProfile(), base::FilePath());
+  if (!profile_)
+    return;
+
+  chromeos::LaunchNoteTakingAppForNewNote(profile_, base::FilePath());
 }
 
 bool PaletteDelegateChromeOS::HasNoteApp() {
-  return chromeos::IsNoteTakingAppAvailable(GetProfile());
+  if (!profile_)
+    return false;
+
+  return chromeos::IsNoteTakingAppAvailable(profile_);
+}
+
+void PaletteDelegateChromeOS::ActiveUserChanged(const AccountId& account_id) {
+  const user_manager::User* user =
+      user_manager::UserManager::Get()->FindUser(account_id);
+  Profile* profile = ProfileHelper::Get()->GetProfileByUser(user);
+  SetProfile(profile);
+}
+
+void PaletteDelegateChromeOS::Observe(
+    int type,
+    const content::NotificationSource& source,
+    const content::NotificationDetails& details) {
+  switch (type) {
+    case chrome::NOTIFICATION_SESSION_STARTED:
+      // Update |profile_| when entering a session.
+      SetProfile(ProfileManager::GetActiveUserProfile());
+
+      // Add a session state observer to be able to monitor session changes.
+      if (!session_state_observer_.get() && ash::Shell::HasInstance()) {
+        session_state_observer_.reset(
+            new ash::ScopedSessionStateObserver(this));
+      }
+      break;
+    case chrome::NOTIFICATION_PROFILE_DESTROYED: {
+      // Update |profile_| when exiting a session or shutting down.
+      Profile* profile = content::Source<Profile>(source).ptr();
+      if (profile_ == profile)
+        SetProfile(nullptr);
+      break;
+    }
+  }
+}
+
+void PaletteDelegateChromeOS::OnPaletteEnabledPrefChanged() {
+  if (profile_) {
+    palette_enabled_callback_list_.Notify(
+        profile_->GetPrefs()->GetBoolean(prefs::kEnableStylusTools));
+  }
+}
+
+void PaletteDelegateChromeOS::SetProfile(Profile* profile) {
+  profile_ = profile;
+  pref_change_registrar_.reset();
+  if (!profile_)
+    return;
+
+  PrefService* prefs = profile_->GetPrefs();
+  pref_change_registrar_.reset(new PrefChangeRegistrar);
+  pref_change_registrar_->Init(prefs);
+  pref_change_registrar_->Add(
+      prefs::kEnableStylusTools,
+      base::Bind(&PaletteDelegateChromeOS::OnPaletteEnabledPrefChanged,
+                 base::Unretained(this)));
+
+  // Run listener with new pref value, if any.
+  OnPaletteEnabledPrefChanged();
 }
 
 void PaletteDelegateChromeOS::SetPartialMagnifierState(bool enabled) {
@@ -52,8 +128,10 @@ void PaletteDelegateChromeOS::SetStylusStateChangedCallback(
 }
 
 bool PaletteDelegateChromeOS::ShouldAutoOpenPalette() {
-  return GetProfile()->GetPrefs()->GetBoolean(
-      prefs::kLaunchPaletteOnEjectEvent);
+  if (!profile_)
+    return false;
+
+  return profile_->GetPrefs()->GetBoolean(prefs::kLaunchPaletteOnEjectEvent);
 }
 
 void PaletteDelegateChromeOS::TakeScreenshot() {