Remove landing page from history when redirecting to NTP so that the back-button will work as expec…

chrome/browser/ui/sync/one_click_signin_helper.cc

 // Copyright (c) 2012 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/sync/one_click_signin_helper.h"
 
 #include <algorithm>
 #include <functional>
 #include <utility>
 #include <vector>
@@ skipping 380 matching lines @@
   GURL clean_one_click_url =
       GURL(GaiaUrls::GetInstance()->gaia_login_form_realm() +
            "ChromeLoginPrompt").ReplaceComponents(replacements);
 
   return (url.ReplaceComponents(replacements) == clean_login_url &&
           source != SyncPromoUI::SOURCE_UNKNOWN) ||
       (url.ReplaceComponents(replacements) == clean_one_click_url &&
        !email.empty());
 }
 
+
+// Watch a webcontents and remove URL from the history once loading is complete.
+// We have to delay the cleaning until the new URL has finished loading because
+// we're not allowed to remove the last-loaded URL from the history.  Objects
+// of this type automatically self-destruct once they're finished their work.
+class CurrentHistoryCleaner : public content::WebContentsObserver {
+ public:
+  explicit CurrentHistoryCleaner(content::WebContents* contents);
+
+  virtual void WebContentsDestroyed(content::WebContents* contents) OVERRIDE;
+  virtual void DidStopLoading(content::RenderViewHost* render_view_host)
+      OVERRIDE;
+
+ private:
+  scoped_ptr<content::WebContents> contents_;
+  int history_index_to_remove_;
+
+  DISALLOW_COPY_AND_ASSIGN(CurrentHistoryCleaner);
+};
+
+
+CurrentHistoryCleaner::CurrentHistoryCleaner(content::WebContents* contents)
+    : WebContentsObserver(contents) {
+  content::NavigationController& nc = web_contents()->GetController();
+  history_index_to_remove_ = nc.GetLastCommittedEntryIndex();
+}
+
+void CurrentHistoryCleaner::DidStopLoading(
+    content::RenderViewHost* render_view_host) {
+  content::NavigationController& nc = web_contents()->GetController();
+  // Have to wait until something else gets added to history before removal.
+  if (history_index_to_remove_ != nc.GetLastCommittedEntryIndex()) {
+    nc.RemoveEntryAtIndex(history_index_to_remove_);
+    Observe(NULL);
+    delete this;  /* success */
+  }
+}
+
+void CurrentHistoryCleaner::WebContentsDestroyed(
+    content::WebContents* contents) {
+  Observe(NULL);
+  delete this;  /* failure */
+}
+
 }  // namespace
 
 // The infobar asking the user if they want to use one-click sign in.
 // TODO(rogerta): once we move to a web-based sign in flow, we can get rid
 // of this infobar.
 class OneClickInfoBarDelegateImpl : public OneClickSigninInfoBarDelegate {
  public:
   // Creates a one click signin delegate and adds it to |infobar_service|.
   static void Create(InfoBarService* infobar_service,
                      const std::string& session_index,
@@ skipping 553 matching lines @@
   if (!session_index.empty())
     helper->session_index_ = session_index;
 
   if (!email.empty())
     helper->email_ = email;
 
   if (continue_url.is_valid())
     helper->continue_url_ = continue_url;
 }
 
+// static
+void OneClickSigninHelper::RemoveCurrentHistoryItem(
+    content::WebContents* web_contents) {
+  new CurrentHistoryCleaner(web_contents);  // will self-destruct when finished
+}
+
 void OneClickSigninHelper::RedirectToNtpOrAppsPage(bool show_bubble) {
   VLOG(1) << "OneClickSigninHelper::RedirectToNtpOrAppsPage";
 
   // Redirect to NTP/Apps page with sign in bubble visible.
   content::WebContents* contents = web_contents();
   Profile* profile =
       Profile::FromBrowserContext(contents->GetBrowserContext());
   PrefService* pref_service = profile->GetPrefs();
   if (show_bubble) {
     pref_service->SetBoolean(prefs::kSyncPromoShowNTPBubble, true);
     pref_service->SetString(prefs::kSyncPromoErrorMessage, error_message_);
   }
 
   GURL url(chrome::IsInstantExtendedAPIEnabled() ?
            chrome::kChromeUIAppsURL : chrome::kChromeUINewTabURL);
   content::OpenURLParams params(url,
                                 content::Referrer(),
                                 CURRENT_TAB,
                                 content::PAGE_TRANSITION_AUTO_TOPLEVEL,
                                 false);
+  RemoveCurrentHistoryItem(contents);
   contents->OpenURL(params);
 
   error_message_.clear();
 }
 
 void OneClickSigninHelper::RedirectToSignin() {
   VLOG(1) << "OneClickSigninHelper::RedirectToSignin";
 
   // Extract the existing sounce=X value.  Default to "2" if missing.
   SyncPromoUI::Source source =
@@ skipping 384 matching lines @@
 
 void OneClickSigninHelper::SigninSuccess() {
   RedirectOnSigninComplete(true);
 }
 
 void OneClickSigninHelper::RedirectOnSigninComplete(bool show_bubble) {
   // Show the result in the sign-in bubble if desired.
   RedirectToNtpOrAppsPage(show_bubble);
   signin_tracker_.reset();
 }