[ios] Prevents history navigation items from being voice-over selectable while not visible.

ios/chrome/browser/ui/history/history_panel_view_controller.mm

 // Copyright 2016 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/ui/history/history_panel_view_controller.h"
 
 #include "base/ios/block_types.h"
 #include "base/ios/ios_util.h"
 #include "base/mac/scoped_nsobject.h"
 #include "components/strings/grit/components_strings.h"
@@ skipping 27 matching lines @@
   // Privacy settings, or "Edit" for entering a mode for deleting individual
   // entries. When in edit mode, the bar displays options to Delete or Cancel.
   base::scoped_nsobject<ClearBrowsingBar> _clearBrowsingBar;
   // View controller for the search bar.
   base::scoped_nsobject<HistorySearchViewController> _searchViewController;
   // Container view for history collection and clear browsing button to enable
   // use of autolayout in conjuction with Material App Bar.
   base::scoped_nsobject<UIView> _containerView;
   // The header view.
   base::scoped_nsobject<MDCAppBar> _appBar;
+  // Left bar button item for Search.
+  base::scoped_nsobject<UIBarButtonItem> _leftBarButtonItem;
+  // Right bar button item for Dismiss history action.
+  base::scoped_nsobject<UIBarButtonItem> _rightBarButtonItem;
 }
 // Closes history.
 - (void)closeHistory;
 // Closes history, invoking completionHandler once dismissal is complete.
 - (void)closeHistoryWithCompletion:(ProceduralBlock)completionHandler;
 // Opens Privacy settings.
 - (void)openPrivacySettings;
 // Configure view for editing mode.
 - (void)enterEditingMode;
 // Configure view for non-editing mode.
@@ skipping 80 matching lines @@
   [_clearBrowsingBar setTranslatesAutoresizingMaskIntoConstraints:NO];
   [_containerView addSubview:_clearBrowsingBar];
   [self configureClearBrowsingBar];
 
   ConfigureAppBarWithCardStyle(_appBar);
   [_appBar headerViewController].headerView.trackingScrollView =
       [_historyCollectionController collectionView];
   [_appBar addSubviewsToParent];
 
   // Add navigation bar buttons.
-  self.navigationItem.leftBarButtonItem =
-      [ChromeIcon templateBarButtonItemWithImage:[ChromeIcon searchIcon]
-                                          target:self
-                                          action:@selector(enterSearchMode)];
-  self.navigationItem.rightBarButtonItem = [[[UIBarButtonItem alloc]
+  _leftBarButtonItem.reset([[ChromeIcon
+      templateBarButtonItemWithImage:[ChromeIcon searchIcon]
+                              target:self
+                              action:@selector(enterSearchMode)] retain]);
+  self.navigationItem.leftBarButtonItem = _leftBarButtonItem;
+  _rightBarButtonItem.reset([[UIBarButtonItem alloc]
       initWithTitle:l10n_util::GetNSString(IDS_IOS_NAVIGATION_BAR_DONE_BUTTON)
               style:UIBarButtonItemStylePlain
              target:self
-             action:@selector(closeHistory)] autorelease];
+             action:@selector(closeHistory)]);
+  self.navigationItem.rightBarButtonItem = _rightBarButtonItem;
   [self configureNavigationBar];
 }
 
 - (void)updateViewConstraints {
   NSDictionary* views = @{
     @"collectionView" : [_historyCollectionController view],
     @"clearBrowsingBar" : _clearBrowsingBar,
   };
   NSArray* constraints = @[
     @"V:|[collectionView][clearBrowsingBar(==48)]|", @"H:|[collectionView]|",
@@ skipping 177 matching lines @@
       _appBar.get().headerViewController.headerView;
   NSArray* constraints = @[
     [[searchBarView topAnchor] constraintEqualToAnchor:headerView.topAnchor],
     [[searchBarView leadingAnchor]
         constraintEqualToAnchor:headerView.leadingAnchor],
     [[searchBarView heightAnchor]
         constraintEqualToAnchor:headerView.heightAnchor],
     [[searchBarView widthAnchor] constraintEqualToAnchor:headerView.widthAnchor]
   ];
   [NSLayoutConstraint activateConstraints:constraints];
+  // Workaround so navigationItems are not voice-over selectable while hidden by
+  // the search view. We might have to re factor the view hierarchy in order to
+  // properly solve this issue. See: https://codereview.chromium.org/2605023002/
+  self.navigationItem.leftBarButtonItem = nil;
+  self.navigationItem.rightBarButtonItem = nil;
 }
 
 - (void)exitSearchMode {
   if (_historyCollectionController.get().searching) {
+    // Resets the navigation items to their initial state.
+    self.navigationItem.leftBarButtonItem = _leftBarButtonItem;
+    self.navigationItem.rightBarButtonItem = _rightBarButtonItem;
+    [self configureNavigationBar];
+
     [[_searchViewController view] removeFromSuperview];
     [_searchViewController removeFromParentViewController];
     _historyCollectionController.get().searching = NO;
     [_historyCollectionController showHistoryMatchingQuery:nil];
   }
 }
 
 - (void)configureNavigationBar {
   // The search button should only be enabled if there are history entries to
   // search, and if history is not in edit mode.
   self.navigationItem.leftBarButtonItem.enabled =
       [_historyCollectionController hasHistoryEntries] &&
       ![_historyCollectionController isEditing];
 }
 
 - (void)configureClearBrowsingBar {
   _clearBrowsingBar.get().editing = _historyCollectionController.get().editing;
   _clearBrowsingBar.get().deleteButtonEnabled =
       [_historyCollectionController hasSelectedEntries];
   _clearBrowsingBar.get().editButtonEnabled =
       [_historyCollectionController hasHistoryEntries];
 }
 
 @end