[ios] Adds VoiceSearchBar creation methods to VoiceSearchProvider.

ios/public/provider/chrome/browser/voice/voice_search_provider.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_VOICE_VOICE_SEARCH_PROVIDER_H_
 #define IOS_PUBLIC_PROVIDER_CHROME_BROWSER_VOICE_VOICE_SEARCH_PROVIDER_H_
 
 #include <Foundation/Foundation.h>
+#include <UIKit/UIKit.h>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 
 class AudioSessionController;
+@protocol VoiceSearchBar;
 class VoiceSearchController;
 
 namespace ios {
 class ChromeBrowserState;
 }
 
 // VoiceSearchProvider allows embedders to provide functionality related to
 // voice search.
 class VoiceSearchProvider {
  public:
   VoiceSearchProvider() = default;
   virtual ~VoiceSearchProvider() = default;
 
   // Returns the list of available voice search languages.
   virtual NSArray* GetAvailableLanguages() const;
 
   // Returns the singleton audio session controller.
   virtual AudioSessionController* GetAudioSessionController() const;
 
   // Creates a new VoiceSearchController object.
   virtual scoped_refptr<VoiceSearchController> CreateVoiceSearchController(
       ios::ChromeBrowserState* browser_state) const;
 
+  // Creates a new VoiceSearchBar.  The caller assumes ownership.
+  virtual UIView<VoiceSearchBar>* CreateVoiceSearchBar(CGRect frame) const
+      NS_RETURNS_RETAINED;

[kkhorimoto, 2016/10/27 17:22:47]

is NS_RETURNS_RETAINED an ARC-related annotation?  It might be worthwhile
sending out a PSA on when to use these for interfacing between C++ and ARC code

[rohitrao (ping after 24h), 2016/10/27 17:47:28]

I've been cargo-culting it.  Will check with stk about sending out a PSA.  I
think it's helpful for him as he manually migrates files, but it may not
directly affect correctness?

+
  private:
   DISALLOW_COPY_AND_ASSIGN(VoiceSearchProvider);
 };
 
 #endif  // IOS_PUBLIC_PROVIDER_CHROME_BROWSER_VOICE_VOICE_SEARCH_PROVIDER_H_