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

public/web/WebLocalFrame.h

 // Copyright 2014 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 WebLocalFrame_h
 #define WebLocalFrame_h
 
 #include "WebFrame.h"
 
 namespace blink {
@@ skipping 90 matching lines @@
     // extension debugging.
     virtual void setIsolatedWorldHumanReadableName(int worldID, const WebString&) = 0;
 
 
     // Selection --------------------------------------------------------------
 
     // Moves the selection extent point. This function does not allow the
     // selection to collapse. If the new extent is set to the same position as
     // the current base, this function will do nothing.
     virtual void moveRangeSelectionExtent(const WebPoint&, TextGranularity = CharacterGranularity) = 0;
+
+
+    // App banner -------------------------------------------------------------
+
+    // Request to show an application install banner for the given |platform|.
+    // The implementation can request the embedder to cancel the call by setting
+    // |cancel| to true.
+    virtual void willShowInstallBannerPrompt(const WebString& platform, bool* cancel) = 0;
 };
 
 } // namespace blink
 
 #endif // WebLocalFrame_h