Expand the footer in the material design Clear Browsing Data dialog.

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)
-    : remover_(nullptr) {
+    : sync_service_(nullptr),
+      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));
+  if (sync_service_)
+    sync_service_->AddObserver(this);

[dschuyler, 2016/04/26 18:47:03]

Rather than adding an observer in the constructor,
please add OnJavascriptAllowed() and OnJavascriptDisallowed()
calls to add and remove observers.

An example is here:
https://codereview.chromium.org/1896463003/diff/120001/chrome/browser/ui/webu...

Further info is here:
https://docs.google.com/document/d/1z1diKvwgMmn4YFzlW1kss0yHmo8yy68TN_FUhUzRz...

[msramek, 2016/04/27 18:10:29]

Done. We're ready for JavaScript callbacks updating the footer after the footer
was first initialized, so I put AllowJavascript() there.

 }
 
 ClearBrowsingDataHandler::~ClearBrowsingDataHandler() {
   if (remover_)
     remover_->RemoveObserver(this);
+  if (sync_service_)
+    sync_service_->RemoveObserver(this);
 }
 
 void ClearBrowsingDataHandler::RegisterMessages() {
   web_ui()->RegisterMessageCallback(
       "clearBrowsingData",
       base::Bind(&ClearBrowsingDataHandler::HandleClearBrowsingData,
                  base::Unretained(this)));
+
+  web_ui()->RegisterMessageCallback(
+      "initializeFooter",
+      base::Bind(&ClearBrowsingDataHandler::InitializeFooter,
+                 base::Unretained(this)));
 }
 
 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 92 matching lines @@
   webui_callback_id_.clear();
 }
 
 void ClearBrowsingDataHandler::OnBrowsingHistoryPrefChanged() {
   web_ui()->CallJavascriptFunction(
       "cr.webUIListenerCallback",
       base::StringValue("browsing-history-pref-changed"),
       base::FundamentalValue(*allow_deleting_browser_history_));
 }
 
+void ClearBrowsingDataHandler::InitializeFooter(const base::ListValue* args) {
+  OnStateChanged();
+  RefreshHistoryNotice();
+}
+
+void ClearBrowsingDataHandler::OnStateChanged() {
+  web_ui()->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();
+}
+
 }  // namespace settings