Fix WebViewTest.CloseOnLoadcommit flakiness.

chrome/test/data/extensions/platform_apps/web_view/close_on_loadcommit/test.js

Index: chrome/test/data/extensions/platform_apps/web_view/close_on_loadcommit/test.js
diff --git a/chrome/test/data/extensions/platform_apps/web_view/close_on_loadcommit/test.js b/chrome/test/data/extensions/platform_apps/web_view/close_on_loadcommit/test.js
index 20ee24e3587909295c1e7f637ddccb203b05812c..5a0b304436ebca41b4d0c37980c8988e2cd11f71 100644
--- a/chrome/test/data/extensions/platform_apps/web_view/close_on_loadcommit/test.js
+++ b/chrome/test/data/extensions/platform_apps/web_view/close_on_loadcommit/test.js
@@ -11,7 +11,11 @@ var launchWindow = function() {
       win.close();
       launchWindow();
     } else {
-      chrome.test.sendMessage('done-close-on-loadcommit');
+      // Due to https://crbug.com/620194, we cannot sendMessage() synchronously
+      // from this callback. Let |win.onload| run before sendMessage is run.
+      setTimeout(function() {
+        chrome.test.sendMessage('done-close-on-loadcommit');
+      }, 0);
     }
   });
 };