Fix iOS builds after ShellView refactor on Android

sky/shell/ios/platform_view_ios.h

 // Copyright 2015 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 SKY_SHELL_PLATFORM_VIEW_IOS_H_
 #define SKY_SHELL_PLATFORM_VIEW_IOS_H_
 
 #include "sky/shell/platform_view.h"
 
 namespace sky {
 namespace shell {
 
 class PlatformViewIOS : public PlatformView {
  public:
+  explicit PlatformViewIOS(const Config& config);
+  ~PlatformViewIOS() override;
   void SurfaceCreated(gfx::AcceleratedWidget widget);
   void SurfaceDestroyed(void);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(PlatformViewIOS);
 };
 
 }  // namespace shell
 }  // namespace sky
 
 #endif  // SKY_SHELL_PLATFORM_VIEW_IOS_H_