Implement webview.captureVisibleRegion()

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

Index: extensions/renderer/resources/guest_view/web_view/web_view.js
diff --git a/extensions/renderer/resources/guest_view/web_view/web_view.js b/extensions/renderer/resources/guest_view/web_view/web_view.js
index 6dd4faeb9c042820c1bde349e480cb0a66d06a93..d55249f2ea0e7fb4962dd6e07741c5c1d20babea 100644
--- a/extensions/renderer/resources/guest_view/web_view/web_view.js
+++ b/extensions/renderer/resources/guest_view/web_view/web_view.js
@@ -31,6 +31,11 @@ WebViewImpl.setupElement = function(proto) {
   // Public-facing API methods.
   var apiMethods = WebViewImpl.getApiMethods();
 
+  // Add the experimental API methods, if available.
+  var experimentalApiMethods =
+      WebViewImpl.maybeGetExperimentalApiMethods();
+  apiMethods = $Array.concat(apiMethods, experimentalApiMethods);
+
   // Create default implementations for undefined API methods.
   var createDefaultApiMethod = function(m) {
     return function(var_args) {
@@ -220,6 +225,9 @@ WebViewImpl.prototype.makeElementFullscreen = function() {
 // Implemented when the ChromeWebView API is available.
 WebViewImpl.prototype.maybeSetupContextMenus = function() {};
 
+// Implemented when the experimental WebView API is available.
+WebViewImpl.maybeGetExperimentalApiMethods = function() { return []; };
+
 GuestViewContainer.registerElement(WebViewImpl);
 
 // Exports.