[ios] Adds ChromiumBrowserProvider.

ios/public/provider/chrome/browser/ui/logo_vendor.h

 // 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.
 
 #ifndef IOS_PUBLIC_PROVIDER_CHROME_BROWSER_UI_LOGO_VENDOR_H_
 #define IOS_PUBLIC_PROVIDER_CHROME_BROWSER_UI_LOGO_VENDOR_H_
 
 #import "ios/public/provider/chrome/browser/voice/logo_animation_controller.h"
 
 @class UIView;
 
 // Defines a controller whose view contains a doodle or search engine logo.
 @protocol LogoVendor<LogoAnimationControllerOwnerOwner, NSObject>
 
 // View that shows a doodle or a search engine logo.
-@property(nonatomic, readonly) UIView* view;
+@property(nonatomic, readonly, retain) UIView* view;
 
 // Whether or not the logo should be shown.  Defaults to YES.
 @property(nonatomic, assign, getter=isShowingLogo) BOOL showingLogo;
 
 // Checks for a new doodle.  Calling this method frequently will result in a
 // query being issued at most once per hour.
 - (void)fetchDoodle;
 
 @end
 
 #endif  // IOS_PUBLIC_PROVIDER_CHROME_BROWSER_UI_LOGO_VENDOR_H_