<webview>: Move back, forward, canGoBack, canGoForward, go from content to chrome

content/test/data/browser_plugin_embedder.html

 <script type="text/javascript">
 function sizeChanged(evt) {
   var data = JSON.parse(evt.detail);
   document.title = "AutoSize(" + data.newWidth + ", " + data.newHeight + ")";
 }
 
 function loadAbort(evt) {
   document.title = JSON.parse(evt.detail).reason;
 }
 function loadStart(evt) {
@@ skipping 25 matching lines @@
 function PostMessage(data, shouldTargetIframe) {
   plugin = document.getElementById('plugin');
   // TODO(fsamuel): contentWindow can be accessed directly once
   // http://wkbug.com/85679 lands.
   if (shouldTargetIframe) {
     plugin.contentWindow.frames[0].postMessage('testing123', '*');
   } else {
     plugin.contentWindow.frames.postMessage('testing123', '*');
   }
 }
-function Back() {
-  var plugin = document.getElementById('plugin');
-  plugin.back();
-}
-function CanGoBack() {
-  var plugin = document.getElementById('plugin');
-  return plugin.canGoBack();
-}
-function CanGoForward() {
-  var plugin = document.getElementById('plugin');
-  return plugin.canGoForward();
-}
-function Forward() {
-  var plugin = document.getElementById('plugin');
-  plugin.forward();
-}
-function Go(relativeIndex) {
-  var plugin = document.getElementById('plugin');
-  plugin.go(relativeIndex);
-}
 function SetTitle(str) {
   document.title = str;
 }
 document.title = 'embedder';
 </script>
 
 <object id="plugin"
     tabindex="0"
     type="application/browser-plugin"
     width="640"
@@ skipping 19 matching lines @@
   }
 }
   var plugin = document.getElementById('plugin');
   plugin.addEventListener('-internal-loadstart', loadStart);
   plugin.addEventListener('-internal-loadabort', loadAbort);
   plugin.addEventListener('-internal-loadredirect', loadRedirect);
   window.addEventListener('message', receiveMessage, false);
   plugin.addEventListener('-internal-loadstop', loadStop);
   plugin.addEventListener('-internal-sizechanged', sizeChanged);
 </script>