Cast Media Router: fix a few issues to pass some tests.

chrome/android/java/src/org/chromium/chrome/browser/media/router/cast/CastRequestIdGenerator.java

Index: chrome/android/java/src/org/chromium/chrome/browser/media/router/cast/CastRequestIdGenerator.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/media/router/cast/CastRequestIdGenerator.java b/chrome/android/java/src/org/chromium/chrome/browser/media/router/cast/CastRequestIdGenerator.java
new file mode 100644
index 0000000000000000000000000000000000000000..c753a838ec3889c5c7a39344c0301f3ef1b54921
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/media/router/cast/CastRequestIdGenerator.java
@@ -0,0 +1,37 @@
+// Copyright 2015 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.
+
+package org.chromium.chrome.browser.media.router.cast;
+
+/**
+ * Returns a request id in a range that is considered fairly unique. These request ids are used to
+ * communicate with the cast device and identify messages and their responses.
+ */
+public class CastRequestIdGenerator {
+    private static final Object LOCK = new Object();
+    private static CastRequestIdGenerator sInstance;
+
+    private int mRequestId;
+
+    /** Returns the next requestId in the range allocated to communicate with the device. */
+    public static int getNextRequestId() {
+        CastRequestIdGenerator instance = getInstance();
+
+        // Return the current |mRequestId| then increment. Never return 0 because it is reserved.
+        if (instance.mRequestId == 0) ++instance.mRequestId;
+        return instance.mRequestId++;
+    }
+
+    /** Returns the Singleton instance of the CastRequestIdGenerator. */
+    private static CastRequestIdGenerator getInstance() {
+        synchronized (LOCK) {
+            if (sInstance == null) sInstance = new CastRequestIdGenerator();
+        }
+        return sInstance;
+    }
+
+    private CastRequestIdGenerator() {
+        mRequestId = (int) Math.floor(Math.random() * 100000.0) * 1000;
+    }
+}