[AppBanner] Blink implementation of an event when an install banner is shown.

Source/web/WebLocalFrameImpl.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 217 matching lines @@
     virtual void setAutofillClient(WebAutofillClient*) override;
     virtual WebAutofillClient* autofillClient() override;
     virtual void sendPings(const WebNode& linkNode, const WebURL& destinationURL) override;
     virtual bool isLoading() const override;
     virtual bool isResourceLoadInProgress() const override;
     virtual void addStyleSheetByURL(const WebString& url) override;
     virtual void navigateToSandboxedMarkup(const WebData& markup) override;
     virtual void sendOrientationChangeEvent() override;
     virtual v8::Handle<v8::Value> executeScriptAndReturnValueForTests(
         const WebScriptSource&) override;
+    virtual void willShowInstallBannerPrompt(const WebString& platform, bool* cancel) override;
 
     void willDetachParent();
 
     static WebLocalFrameImpl* create(WebFrameClient*);
     virtual ~WebLocalFrameImpl();
 
     PassRefPtrWillBeRawPtr<LocalFrame> initializeCoreFrame(FrameHost*, FrameOwner*, const AtomicString& name, const AtomicString& fallbackName);
 
     PassRefPtrWillBeRawPtr<LocalFrame> createChildFrame(const FrameLoadRequest&, HTMLFrameOwnerElement*);
 
@@ skipping 136 matching lines @@
     GC_PLUGIN_IGNORE("340522")
     Persistent<WebLocalFrameImpl> m_selfKeepAlive;
 #endif
 };
 
 DEFINE_TYPE_CASTS(WebLocalFrameImpl, WebFrame, frame, frame->isWebLocalFrame(), frame.isWebLocalFrame());
 
 } // namespace blink
 
 #endif