MD Settings: Update some Settings handlers to use new JS lifecycle management.

chrome/browser/ui/webui/settings/settings_clear_browsing_data_handler.cc

 // Copyright 2015 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 "chrome/browser/ui/webui/settings/settings_clear_browsing_data_handler.h"
 
 #include <stddef.h>
 
 #include "base/macros.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
 #include "chrome/browser/browsing_data/browsing_data_helper.h"
 #include "chrome/browser/browsing_data/browsing_data_remover_factory.h"
 #include "chrome/browser/history/web_history_service_factory.h"
 #include "chrome/browser/sync/profile_sync_service_factory.h"
 #include "chrome/common/pref_names.h"
 #include "components/browsing_data_ui/history_notice_utils.h"
 #include "components/prefs/pref_service.h"
 #include "content/public/browser/web_ui.h"
 
 namespace settings {
 
 ClearBrowsingDataHandler::ClearBrowsingDataHandler(content::WebUI* webui)
     : sync_service_(nullptr),
+      sync_service_observer_(this),
       remover_(nullptr),
       should_show_history_footer_(false),
       weak_ptr_factory_(this) {
   PrefService* prefs = Profile::FromWebUI(webui)->GetPrefs();
   clear_plugin_lso_data_enabled_.Init(prefs::kClearPluginLSODataEnabled, prefs);
   pepper_flash_settings_enabled_.Init(prefs::kPepperFlashSettingsEnabled,
                                       prefs);
-  allow_deleting_browser_history_.Init(
-      prefs::kAllowDeletingBrowserHistory, prefs,
-      base::Bind(&ClearBrowsingDataHandler::OnBrowsingHistoryPrefChanged,
-                 base::Unretained(this)));
   sync_service_ =
         ProfileSyncServiceFactory::GetForProfile(Profile::FromWebUI(webui));
 }
 
 ClearBrowsingDataHandler::~ClearBrowsingDataHandler() {
   if (remover_)
     remover_->RemoveObserver(this);
 }
 
 void ClearBrowsingDataHandler::RegisterMessages() {
   web_ui()->RegisterMessageCallback(
       "clearBrowsingData",
       base::Bind(&ClearBrowsingDataHandler::HandleClearBrowsingData,
                  base::Unretained(this)));
 
   web_ui()->RegisterMessageCallback(
       "initializeClearBrowsingData",
       base::Bind(&ClearBrowsingDataHandler::HandleInitialize,
                  base::Unretained(this)));
 }
 
 void ClearBrowsingDataHandler::OnJavascriptAllowed() {
+  PrefService* prefs = Profile::FromWebUI(web_ui())->GetPrefs();
+  allow_deleting_browser_history_.Init(
+      prefs::kAllowDeletingBrowserHistory, prefs,
+      base::Bind(&ClearBrowsingDataHandler::OnBrowsingHistoryPrefChanged,
+                 base::Unretained(this)));
+
   if (sync_service_)
-    sync_service_->AddObserver(this);
+    sync_service_observer_.Add(sync_service_);
 }
 
 void ClearBrowsingDataHandler::OnJavascriptDisallowed() {
-  if (sync_service_)
-    sync_service_->RemoveObserver(this);
+  allow_deleting_browser_history_.Destroy();
+  sync_service_observer_.RemoveAll();
 }
 
 void ClearBrowsingDataHandler::HandleClearBrowsingData(
     const base::ListValue* args) {
   // We should never be called when the previous clearing has not yet finished.
   CHECK(!remover_);
   CHECK_EQ(1U, args->GetSize());
   CHECK(webui_callback_id_.empty());
   CHECK(args->GetString(0, &webui_callback_id_));
 
@@ skipping 86 matching lines @@
 void ClearBrowsingDataHandler::OnBrowsingDataRemoverDone() {
   remover_->RemoveObserver(this);
   remover_ = nullptr;
   ResolveJavascriptCallback(
       base::StringValue(webui_callback_id_),
       *base::Value::CreateNullValue());
   webui_callback_id_.clear();
 }
 
 void ClearBrowsingDataHandler::OnBrowsingHistoryPrefChanged() {
-  web_ui()->CallJavascriptFunction(
+  // This is lame, but PrefMembers don't support starting/stopping observers.
+  if (!IsJavascriptAllowed())
+    return;

[Dan Beam, 2016/05/11 17:19:57]

^ did you write this before you found Destroy()?

[tommycli, 2016/05/11 17:22:05]

Done. Oops yes exactly. Removed.

+
+  CallJavascriptFunction(
       "cr.webUIListenerCallback",
       base::StringValue("browsing-history-pref-changed"),
       base::FundamentalValue(*allow_deleting_browser_history_));
 }
 
 void ClearBrowsingDataHandler::HandleInitialize(const base::ListValue* args) {
   AllowJavascript();
   OnStateChanged();
   RefreshHistoryNotice();
 }
 
 void ClearBrowsingDataHandler::OnStateChanged() {
-  web_ui()->CallJavascriptFunction(
+  CallJavascriptFunction(
       "cr.webUIListenerCallback",
       base::StringValue("update-footer"),
       base::FundamentalValue(sync_service_ && sync_service_->IsSyncActive()),
       base::FundamentalValue(should_show_history_footer_));
 }
 
 void ClearBrowsingDataHandler::RefreshHistoryNotice() {
   browsing_data_ui::ShouldShowNoticeAboutOtherFormsOfBrowsingHistory(
       sync_service_,
       WebHistoryServiceFactory::GetForProfile(Profile::FromWebUI(web_ui())),
       base::Bind(&ClearBrowsingDataHandler::UpdateHistoryNotice,
                  weak_ptr_factory_.GetWeakPtr()));
 }
 
 void ClearBrowsingDataHandler::UpdateHistoryNotice(bool show) {
   should_show_history_footer_ = show;
   OnStateChanged();
 
   UMA_HISTOGRAM_BOOLEAN(
       "History.ClearBrowsingData.HistoryNoticeShownInFooterWhenUpdated",
       should_show_history_footer_);
 }
 
 }  // namespace settings