Move WebView.captureVisibleRegion to stable API.

extensions/renderer/resources/guest_view/web_view/web_view_api_methods.js

 // 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.
 
 // This module implements the public-facing API functions for the <webview> tag.
 
 var WebViewInternal = require('webViewInternal').WebViewInternal;
 var WebViewImpl = require('webView').WebViewImpl;
 
 // An array of <webview>'s public-facing API methods. Methods without custom
@@ skipping 19 matching lines @@
 
   // Navigates to the previous history entry.
   'back',
 
   // Returns whether there is a previous history entry to navigate to.
   'canGoBack',
 
   // Returns whether there is a subsequent history entry to navigate to.
   'canGoForward',
 
+  // Captures the visible region of the WebView contents into a bitmap.
+  'captureVisibleRegion',
+
   // Clears browsing data for the WebView partition.
   'clearData',
 
   // Injects JavaScript code into the guest page.
   'executeScript',
 
   // Initiates a find-in-page request.
   'find',
 
   // Navigates to the subsequent history entry.
@@ skipping 145 matching lines @@
   this.cachedZoomFactor = 1;
   WebViewInternal.setZoom(this.guest.getId(), zoomFactor, callback);
   return true;
 };
 
 // -----------------------------------------------------------------------------
 
 WebViewImpl.getApiMethods = function() {
   return WEB_VIEW_API_METHODS;
 };