Revert of Relanding "Fixed title updating for back forward navigation."

ios/chrome/browser/tabs/tab.mm

 // Copyright 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.
 
 #import "ios/chrome/browser/tabs/tab.h"
 
 #import <CoreLocation/CoreLocation.h>
 #import <UIKit/UIKit.h>
 
 #include <utility>
@@ skipping 319 matching lines @@
 // in order of priority.
 - (NSArray*)suggestionProviders;
 
 // Returns a list of FormInputAccessoryViewProviders to be queried for an input
 // accessory view in order of priority.
 - (NSArray*)accessoryViewProviders;
 
 // Sets the favicon on the current NavigationItem.
 - (void)setFavicon:(const gfx::Image*)image;
 
+// Updates the title field of the current session entry. Also updates the
+// history database.
+- (void)updateTitle:(NSString*)title;
+
 // Saves the current title to the history database.
 - (void)saveTitleToHistoryDB;
 
 // Adds the current session entry to this history database.
 - (void)addCurrentEntryToHistoryDB;
 
 // Adds any cached entries from |addPageVector_| to the history DB.
 - (void)commitCachedEntriesToHistoryDB;
 
 // Returns the OpenInController for this tab.
@@ skipping 632 matching lines @@
   if (browserState_->IsOffTheRecord()) {
     style = OverscrollStyle::REGULAR_PAGE_INCOGNITO;
   }
   [overscrollActionsController_ setStyle:style];
   [overscrollActionsController_
       setDelegate:overscrollActionsControllerDelegate];
   overscrollActionsControllerDelegate_.reset(
       overscrollActionsControllerDelegate);
 }
 
+- (void)updateTitle:(NSString*)title {
+  web::NavigationItem* item = [self navigationManager]->GetVisibleItem();
+  if (!item)
+    return;
+  item->SetTitle(base::SysNSStringToUTF16(title));
+  // TODO(crbug.com/546218): See if this can be removed; it's not clear that
+  // other platforms send this (tab sync triggers need to be compared against
+  // upstream).
+  if (webStateImpl_)
+    webStateImpl_->GetNavigationManagerImpl().OnNavigationItemChanged();
+
+  [self saveTitleToHistoryDB];
+}
+
 - (void)saveTitleToHistoryDB {
   // If incognito, don't update history.
   if (browserState_->IsOffTheRecord())
     return;
   // Don't update the history if current entry has no title.
   NSString* title = [self title];
   if (![title length] ||
       [title isEqualToString:l10n_util::GetNSString(IDS_DEFAULT_TAB_TITLE)])
     return;
 
@@ skipping 804 matching lines @@
     shouldOpenExternalURL:(const GURL&)URL {
   if (isPrerenderTab_ && !isLinkLoadingPrerenderTab_) {
     [delegate_ discardPrerender];
     return NO;
   }
   return YES;
 }
 
 - (void)webController:(CRWWebController*)webController
        titleDidChange:(NSString*)title {
-  [self saveTitleToHistoryDB];
-  [parentTabModel_ notifyTabChanged:self];
+  NSString* oldTitle = [self title];
+  BOOL isTitleChanged = (!oldTitle && title) || (oldTitle && !title) ||
+                        (![oldTitle isEqualToString:title]);
+  if (isTitleChanged) {
+    [self updateTitle:title];
+    [parentTabModel_ notifyTabChanged:self];
+  }
 }
 
 - (BOOL)urlTriggersNativeAppLaunch:(const GURL&)url
                          sourceURL:(const GURL&)sourceURL
                        linkClicked:(BOOL)linkClicked {
   // Don't open any native app directly when prerendering or from Incognito.
   if (isPrerenderTab_ || self.browserState->IsOffTheRecord())
     return NO;
 
   base::scoped_nsprotocol<id<NativeAppMetadata>> metadata(
@@ skipping 382 matching lines @@
 
 - (TabModel*)parentTabModel {
   return parentTabModel_;
 }
 
 - (FormInputAccessoryViewController*)inputAccessoryViewController {
   return inputAccessoryViewController_.get();
 }
 
 @end