BrowserPluginHostTest: Rewrite 3 focus related tests and 1 visibility test to browser_tests.

chrome/test/data/extensions/platform_apps/web_view/shim/inject_hidden_test.js

Index: chrome/test/data/extensions/platform_apps/web_view/shim/inject_hidden_test.js
diff --git a/chrome/test/data/extensions/platform_apps/web_view/shim/inject_hidden_test.js b/chrome/test/data/extensions/platform_apps/web_view/shim/inject_hidden_test.js
new file mode 100644
index 0000000000000000000000000000000000000000..2c1c94dc9657512ca7bc7dd3c99321133cbaae63
--- /dev/null
+++ b/chrome/test/data/extensions/platform_apps/web_view/shim/inject_hidden_test.js
@@ -0,0 +1,17 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+window.addEventListener('message', function(e) {
+  var response = '';
+  var data = JSON.parse(e.data);
+
+  if (data[0] == 'visibilityState-request') {
+    response = document.visibilityState;
+  } else {
+    response = 'FAILED';
+  }
+
+  e.source.postMessage(
+      JSON.stringify(['visibilityState-response', response]), '*');
+});