[ios] Adds LocationBarCoordinator.

ios/chrome/browser/ui/omnibox/omnibox_view_ios.mm

 // 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 "ios/chrome/browser/ui/omnibox/omnibox_view_ios.h"
 
 #import <CoreText/CoreText.h>
 #import <MobileCoreServices/MobileCoreServices.h>
 
 #include "base/auto_reset.h"
@@ skipping 162 matching lines @@
                                id<OmniboxPopupPositioner> positioner)
     : OmniboxView(
           controller,
           base::MakeUnique<ChromeOmniboxClientIOS>(controller, browser_state)),
       browser_state_(browser_state),
       field_(field),
       controller_(controller),
       preloader_(preloader),
       ignore_popup_updates_(false),
       attributing_display_string_(nil) {
+  DCHECK(field_);
   popup_view_.reset(new OmniboxPopupViewIOS(this, model(), positioner));
   field_delegate_.reset(
       [[AutocompleteTextFieldDelegate alloc] initWithEditView:this]);
   [field_ setDelegate:field_delegate_];
   [field_ addTarget:field_delegate_
                 action:@selector(textFieldDidChange:)
       forControlEvents:UIControlEventEditingChanged];
 }
 
 OmniboxViewIOS::~OmniboxViewIOS() {
@@ skipping 680 matching lines @@
 // is being left out for now because it was not present before the OmniboxView
 // rewrite.
 #if 0
   // When editing is in progress, the url text is not colored, so there is
   // nothing to emphasize.  (Calling SetText() in that situation would also be
   // harmful, as it would reset the carat position to the end of the text.)
   if (!IsEditingOrEmpty())
     SetText(GetText());
 #endif
 }