Gmail mails get modified upon send due to certain extensions

chrome/test/data/extensions/api_test/content_scripts/about_blank_iframes/test.html

Index: chrome/test/data/extensions/api_test/content_scripts/about_blank_iframes/test.html
===================================================================
--- chrome/test/data/extensions/api_test/content_scripts/about_blank_iframes/test.html	(revision 0)
+++ chrome/test/data/extensions/api_test/content_scripts/about_blank_iframes/test.html	(revision 0)
@@ -0,0 +1,22 @@
+<script>
+chrome.test.getConfig(function(config) {
+  chrome.test.runTests([
+    function onRequest() {
+      chrome.extension.onRequest.addListener(
+        function(request, sender, sendResponse) {
+          if (request == "parent")
+            chrome.test.succeed();
+          else
+            chrome.test.fail("Unexpected request: " + JSON.stringify(request));
+        }
+      );
+      chrome.test.log("Creating tab...");
+      var test_url =
+          ("http://localhost:PORT/files/extensions/" +
+           "test_file_with_about_blank_iframe.html")
+              .replace(/PORT/, config.testServer.port);
+      chrome.tabs.create({ url: test_url });
+    }
+  ]);
+});
+</script>