Cherry-picked remaining parts of 'Fixed title updating for back forward navigation.'

ios/web/web_state/ui/crw_web_controller.mm

Index: ios/web/web_state/ui/crw_web_controller.mm
diff --git a/ios/web/web_state/ui/crw_web_controller.mm b/ios/web/web_state/ui/crw_web_controller.mm
index 1f20df56c0032658f45927fa4d62cfa0d7e43a85..3e85b266568658499e98974d12770f8dc29bd0be 100644
--- a/ios/web/web_state/ui/crw_web_controller.mm
+++ b/ios/web/web_state/ui/crw_web_controller.mm
@@ -739,8 +739,9 @@ typedef void (^ViewportStateCompletion)(const web::PageViewportState*);
                     stateObject:(NSString*)stateObject;
 // Sets _documentURL to newURL, and updates any relevant state information.
 - (void)setDocumentURL:(const GURL&)newURL;
-// Sets WKWebView's title to the last committed navigation item.
-- (void)updateNavigationItemTitle;
+// Sets last committed NavigationItem's title to the given |title|, which can
+// not be nil.
+- (void)setNavigationItemTitle:(NSString*)title;
 // Returns YES if the current navigation item corresponds to a web page
 // loaded by a POST request.
 - (BOOL)isCurrentNavigationItemPOST;
@@ -1423,15 +1424,14 @@ const NSTimeInterval kSnapshotOverlayTransition = 0.5;
   }
 }
 
-- (void)updateNavigationItemTitle {
-  NSString* webViewTitle = [_webView title];
-  DCHECK(webViewTitle);
+- (void)setNavigationItemTitle:(NSString*)title {
+  DCHECK(title);
   auto& navigationManager = _webStateImpl->GetNavigationManagerImpl();
   web::NavigationItem* item = navigationManager.GetLastCommittedItem();
   if (!item)
     return;
 
-  base::string16 newTitle = base::SysNSStringToUTF16(webViewTitle);
+  base::string16 newTitle = base::SysNSStringToUTF16(title);
   if (item->GetTitle() == newTitle)
     return;
 
@@ -1442,7 +1442,7 @@ const NSTimeInterval kSnapshotOverlayTransition = 0.5;
   navigationManager.OnNavigationItemChanged();
 
   if ([_delegate respondsToSelector:@selector(webController:titleDidChange:)]) {
-    [_delegate webController:self titleDidChange:webViewTitle];
+    [_delegate webController:self titleDidChange:title];
   }
 }
 
@@ -1870,14 +1870,13 @@ const NSTimeInterval kSnapshotOverlayTransition = 0.5;
   // Perform post-load-finished updates.
   [self didFinishWithURL:currentURL loadSuccess:loadSuccess];
 
-  // Inform the embedder the title changed.
+  NSString* title = [self.nativeController title];
+  if (title)
+    [self setNavigationItemTitle:title];
+
+  // If the controller handles title change notification, route those to the
+  // delegate.
   if ([_delegate respondsToSelector:@selector(webController:titleDidChange:)]) {
-    NSString* title = [self.nativeController title];
-    // If a title is present, notify the delegate.
-    if (title)
-      [_delegate webController:self titleDidChange:title];
-    // If the controller handles title change notification, route those to the
-    // delegate.
     if ([self.nativeController respondsToSelector:@selector(setDelegate:)]) {
       [self.nativeController setDelegate:self];
     }
@@ -4982,7 +4981,6 @@ const NSTimeInterval kSnapshotOverlayTransition = 0.5;
   // This is the point where the document's URL and title have actually changed,
   // and pending navigation information should be applied to state information.
   [self setDocumentURL:net::GURLWithNSURL([_webView URL])];
-  [self updateNavigationItemTitle];
 
   if (!_lastRegisteredRequestURL.is_valid() &&
       _documentURL != _lastRegisteredRequestURL) {
@@ -5025,6 +5023,10 @@ const NSTimeInterval kSnapshotOverlayTransition = 0.5;
   // Attempt to update the HTML5 history state.
   [self updateHTML5HistoryState];
 
+  // This is the point where pending entry has been committed, and navigation
+  // item title should be updated.
+  [self setNavigationItemTitle:[_webView title]];
+
   // Report cases where SSL cert is missing for a secure connection.
   if (_documentURL.SchemeIsCryptographic()) {
     scoped_refptr<net::X509Certificate> cert =
@@ -5225,7 +5227,7 @@ const NSTimeInterval kSnapshotOverlayTransition = 0.5;
   if (hasPendingNavigation) {
     // Do not update the title if there is a navigation in progress because
     // there is no way to tell if KVO change fired for new or previous page.
-    [self updateNavigationItemTitle];
+    [self setNavigationItemTitle:[_webView title]];
   }
 }