When creating a tab contents for a browser in the RVHDelegateHelper, create a wrapper immediately.

chrome/test/data/extensions/api_test/webrequest/test_newTab.html

+<script src="framework.js">
+</script>
+<script>
+runTests([
+  // Navigates to a page with a link with target=_blank. Then simulates a click
+  // on that link and verifies that the new tab has a correct tab ID assigned.
+  function () {
+    expect(
+      [  // events
+        { label: "a-onBeforeRequest",
+          event: "onBeforeRequest",
+          details: {
+            url: getURL("newTab/a.html"),
+            frameUrl: getURL("newTab/a.html")
+          }
+        },
+        { label: "a-onResponseStarted",
+          event: "onResponseStarted",
+          details: {
+            url: getURL("newTab/a.html"),
+            statusCode: 200,
+            fromCache: false,
+            statusLine: "HTTP/1.1 200 OK",
+            // Request to chrome-extension:// url has no IP.
+          }
+        },
+        { label: "a-onCompleted",
+          event: "onCompleted",
+          details: {
+            url: getURL("newTab/a.html"),
+            statusCode: 200,
+            fromCache: false,
+            statusLine: "HTTP/1.1 200 OK",
+            // Request to chrome-extension:// url has no IP.
+          }
+        },
+        { label: "b-onBeforeRequest",
+          event: "onBeforeRequest",
+          details: {
+            url: getURL("newTab/b.html"),
+            frameUrl: getURL("newTab/b.html"),
+            tabId: 1,
+          }
+        },
+        { label: "b-onResponseStarted",
+          event: "onResponseStarted",
+          details: {
+            url: getURL("newTab/b.html"),
+            statusCode: 200,
+            fromCache: false,
+            statusLine: "HTTP/1.1 200 OK",
+            // Request to chrome-extension:// url has no IP.
+            tabId: 1,
+          }
+        },
+        { label: "b-onCompleted",
+          event: "onCompleted",
+          details: {
+            url: getURL("newTab/b.html"),
+            statusCode: 200,
+            fromCache: false,
+            statusLine: "HTTP/1.1 200 OK",
+            // Request to chrome-extension:// url has no IP.
+            tabId: 1,
+          }
+        },
+      ],
+      [  // event order
+      ["a-onBeforeRequest", "a-onResponseStarted", "a-onCompleted",
+       "b-onBeforeRequest", "b-onResponseStarted", "b-onCompleted"] ]);
+    // Notify the api test that we're waiting for the user.
+    chrome.test.notifyPass();
+  },
+]);
+</script>