Let modal view controllers become first responder when presented.

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/metrics/user_metrics.h"
 #include "base/metrics/user_metrics_action.h"
@@ skipping 391 matching lines @@
 - (void)configureClearBrowsingBar {
   _clearBrowsingBar.editing = _historyCollectionController.editing;
   _clearBrowsingBar.deleteButtonEnabled =
       [_historyCollectionController hasSelectedEntries];
   _clearBrowsingBar.editButtonEnabled =
       [_historyCollectionController hasHistoryEntries];
 }
 
 #pragma mark - UIResponder
 
+- (BOOL)canBecomeFirstResponder {
+  return YES;
+}
+
 - (NSArray*)keyCommands {
   __weak HistoryPanelViewController* weakSelf = self;
   return @[ [UIKeyCommand cr_keyCommandWithInput:UIKeyInputEscape
                                    modifierFlags:Cr_UIKeyModifierNone
                                            title:nil
                                           action:^{
                                             [weakSelf closeHistory];
                                           }] ];
 }
 
 @end