Implement a basic PPAPI plugin for Blink layout tests.

third_party/WebKit/LayoutTests/plugins/webview-plugin-type-change.html

Index: third_party/WebKit/LayoutTests/plugins/webview-plugin-type-change.html
diff --git a/third_party/WebKit/LayoutTests/plugins/webview-plugin-type-change.html b/third_party/WebKit/LayoutTests/plugins/webview-plugin-type-change.html
index 6441b55cb35a3774f53039277c154fb8bb2cf88c..34b05da5ba15055ec59403898489ba63dcb0d78b 100644
--- a/third_party/WebKit/LayoutTests/plugins/webview-plugin-type-change.html
+++ b/third_party/WebKit/LayoutTests/plugins/webview-plugin-type-change.html
@@ -8,18 +8,15 @@
 </style>
 <embed id="plugin"></embed>
 <script>
+document.querySelector('embed').addEventListener('message', function(message) {
+    if (message.data == 'loaded')
+        if (window.testRunner)
+            window.testRunner.notifyDone();
+});
 onload = function() {
-    document.getElementById("plugin").setAttribute('type', 'application/x-webkit-test-netscape');
+    document.getElementById('plugin').setAttribute('type', 'application/x-blink-test-plugin');
 
-    if (window.testRunner) {
+    if (window.testRunner)
         window.testRunner.waitUntilDone();
-        // Need to paint two frames in order to allow the plugin to propery load.
-        // TODO(chrishtr): find out why and fix.
-        window.testRunner.layoutAndPaintAsyncThen(function() {
-            window.testRunner.layoutAndPaintAsyncThen(function() {
-                window.testRunner.notifyDone();
-            });
-        });
-    }
 }
-</script>
+</script>