[Android] Upstream remaining changes to NTP UI code.

chrome/browser/ui/webui/ntp/recently_closed_tabs_handler.cc

Index: chrome/browser/ui/webui/ntp/recently_closed_tabs_handler.cc
diff --git a/chrome/browser/ui/webui/ntp/recently_closed_tabs_handler.cc b/chrome/browser/ui/webui/ntp/recently_closed_tabs_handler.cc
index da09744e60dae6808d26eb6ed504d4edfb1ae5bf..24e00ecf6e2036b19c184e14f75168d7d879a51f 100644
--- a/chrome/browser/ui/webui/ntp/recently_closed_tabs_handler.cc
+++ b/chrome/browser/ui/webui/ntp/recently_closed_tabs_handler.cc
@@ -57,6 +57,9 @@ void RecentlyClosedTabsHandler::RegisterMessages() {
   web_ui()->RegisterMessageCallback("reopenTab",
       base::Bind(&RecentlyClosedTabsHandler::HandleReopenTab,
                  base::Unretained(this)));
+  web_ui()->RegisterMessageCallback("clearRecentlyClosed",
+      base::Bind(&RecentlyClosedTabsHandler::HandleClearRecentlyClosed,
+                 base::Unretained(this)));
 }
 
 RecentlyClosedTabsHandler::~RecentlyClosedTabsHandler() {
@@ -68,13 +71,6 @@ void RecentlyClosedTabsHandler::HandleReopenTab(const ListValue* args) {
   if (!tab_restore_service_)
     return;
 
-  double index = -1.0;
-  CHECK(args->GetDouble(1, &index));
-
-  // There are actually less than 20 restore tab items displayed in the UI.
-  UMA_HISTOGRAM_ENUMERATION("NewTabPage.SessionRestore",
-                            static_cast<int>(index), 20);
-
   double session_to_restore = 0.0;
   CHECK(args->GetDouble(0, &session_to_restore));
 
@@ -95,6 +91,13 @@ void RecentlyClosedTabsHandler::HandleReopenTab(const ListValue* args) {
   SessionRestore::RestoreForeignSessionTab(web_ui()->GetWebContents(),
                                            session_tab, NEW_FOREGROUND_TAB);
 #else
+  double index = -1.0;
+  CHECK(args->GetDouble(1, &index));
+
+  // There are actually less than 20 restore tab items displayed in the UI.
+  UMA_HISTOGRAM_ENUMERATION("NewTabPage.SessionRestore",
+                            static_cast<int>(index), 20);
+
   TabRestoreServiceDelegate* delegate =
       TabRestoreServiceDelegate::FindDelegateForWebContents(
           web_ui()->GetWebContents());
@@ -110,23 +113,16 @@ void RecentlyClosedTabsHandler::HandleReopenTab(const ListValue* args) {
 #endif
 }
 
-void RecentlyClosedTabsHandler::HandleGetRecentlyClosedTabs(
+void RecentlyClosedTabsHandler::HandleClearRecentlyClosed(
     const ListValue* args) {
-  if (!tab_restore_service_) {
-    tab_restore_service_ =
-        TabRestoreServiceFactory::GetForProfile(Profile::FromWebUI(web_ui()));
-
-    // TabRestoreServiceFactory::GetForProfile() can return NULL (i.e., when in
-    // Off the Record mode)
-    if (tab_restore_service_) {
-      // This does nothing if the tabs have already been loaded or they
-      // shouldn't be loaded.
-      tab_restore_service_->LoadTabsFromLastSession();
-
-      tab_restore_service_->AddObserver(this);
-    }
-  }
+  EnsureTabRestoreService();
+  if (tab_restore_service_)
+    tab_restore_service_->ClearEntries();
+}
 
+void RecentlyClosedTabsHandler::HandleGetRecentlyClosedTabs(
+    const ListValue* args) {
+  EnsureTabRestoreService();
   if (tab_restore_service_)
     TabRestoreServiceChanged(tab_restore_service_);
 }
@@ -171,3 +167,20 @@ void RecentlyClosedTabsHandler::CreateRecentlyClosedValues(
     added_count++;
   }
 }
+
+void RecentlyClosedTabsHandler::EnsureTabRestoreService() {
+  if (tab_restore_service_)
+    return;
+
+  tab_restore_service_ =
+      TabRestoreServiceFactory::GetForProfile(Profile::FromWebUI(web_ui()));
+
+  // TabRestoreServiceFactory::GetForProfile() can return NULL (i.e., when in
+  // Off the Record mode)
+  if (tab_restore_service_) {
+    // This does nothing if the tabs have already been loaded or they
+    // shouldn't be loaded.
+    tab_restore_service_->LoadTabsFromLastSession();
+    tab_restore_service_->AddObserver(this);
+  }
+}