Porting ppapi_tests framework to postMessage.

ppapi/tests/test_post_message.cc

Index: ppapi/tests/test_post_message.cc
diff --git a/ppapi/tests/test_post_message.cc b/ppapi/tests/test_post_message.cc
index a97ba420cf4cd92c36c1174646bd905e33fc68ed..ea298820efe442299c69b7e40bc71f76f0516b33 100644
--- a/ppapi/tests/test_post_message.cc
+++ b/ppapi/tests/test_post_message.cc
@@ -44,11 +44,18 @@ void TestPostMessage::HandleMessage(const pp::Var& message_data) {
 
 bool TestPostMessage::AddEchoingListener(const std::string& expression) {
   std::string js_code;
+  // Note the following code is dependent on some features of test_case.html.
+  // E.g., it is assumed that the DOM element where the plugin is embedded has
+  // an id of 'plugin', and there is a function 'IsTestingMessage' that allows
+  // us to ignore the messages that are intended for use by the testing
+  // framework itself.
   js_code += "var plugin = document.getElementById('plugin');"
              "var message_handler = function(message_event) {"
-             "  plugin.postMessage(";
+             "  if (!IsTestingMessage(message_event.data)) {"
+             "    plugin.postMessage(";
   js_code += expression;
-  js_code += "  );"
+  js_code += "                      );"
+             "  }"
              "};"
              "plugin.addEventListener('message', message_handler);"
              // Maintain an array of all event listeners, attached to the