[chrome.displaySource] Add example extension

chrome/common/extensions/docs/examples/api/displaySource/tabCast/main.css

Index: chrome/common/extensions/docs/examples/api/displaySource/tabCast/main.css
diff --git a/chrome/common/extensions/docs/examples/api/displaySource/tabCast/main.css b/chrome/common/extensions/docs/examples/api/displaySource/tabCast/main.css
new file mode 100644
index 0000000000000000000000000000000000000000..70cd2020260d8913e01560dc8336cf889f7359f8
--- /dev/null
+++ b/chrome/common/extensions/docs/examples/api/displaySource/tabCast/main.css
@@ -0,0 +1,60 @@
+/* Copyright 2016 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.
+ */
+
+.connecting {
+  animation: glowing 1500ms infinite;
+  background-color: #004A7F;
+  border-radius: 10px;
+  border: none;
+  color: #FFFFFF;
+  cursor: pointer;
+  font-size: 20px;
+  margin: 1px;
+  outline: none;
+  padding: 5px 10px;
+  width: 170px;
+}
+
+.disconnected {
+  background-color: #004A7F;
+  border-radius: 10px;
+  border: none;
+  color: #FFFFFF;
+  cursor: pointer;
+  font-size: 20px;
+  margin: 1px;
+  outline: none;
+  padding: 5px 10px;
+  width: 170px;
+}
+
+.connected {
+  background-color: #0094FF;
+  border-radius: 10px;
+  border: none;
+  box-shadow: 0 0 20px #0094FF;
+  color: #FFFFFF;
+  cursor: pointer;
+  font-size: 20px;
+  margin: 1px;
+  outline: none;
+  padding: 5px 10px;
+  width: 170px;
+}
+
+@keyframes glowing {
+  0% {
+    background-color: #004A7F;
+    box-shadow: 0 0 3px #004A7F;
+  }
+  50% {
+    background-color: #0094FF;
+    box-shadow: 0 0 10px #0094FF;
+  }
+  100% {
+    background-color: #004A7F;
+    box-shadow: 0 0 3px #004A7F;
+  }
+}