Add the Physical Web to Chrome on Android

chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PhysicalWebBleClient.java

Index: chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PhysicalWebBleClient.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PhysicalWebBleClient.java b/chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PhysicalWebBleClient.java
new file mode 100644
index 0000000000000000000000000000000000000000..ce095386d9c24eccaa31b04424c1ee866e5f1bf7
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PhysicalWebBleClient.java
@@ -0,0 +1,48 @@
+// 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.physicalweb;
+
+import android.app.Application;
+
+import org.chromium.base.Log;
+import org.chromium.chrome.browser.ChromeApplication;
+
+import java.util.concurrent.atomic.AtomicReference;
+
+/**
+ * The Client that harvests URLs from BLE signals.
+ * This class is designed to scan URSs from Bluetooth Low Energy beacons.
+ * This class is currently an empty implementation and must be extended by a
+ * subclass.
+ */
+public class PhysicalWebBleClient {
+    private static AtomicReference<PhysicalWebBleClient> sInstance =
+            new AtomicReference<PhysicalWebBleClient>();
+    private static final String TAG = "PhysicalWeb";
+
+    /**
+     * Get a singleton instance of this class.
+     * @param application An instance of {@link Application}, which should be a
+     * {@link ChromeApplication}, used to get the appropriate PhysicalWebBleClient
+     * implementation.
+     * @return an instance of this class (or subclass) as decided by the
+     * application parameter
+     */
+    public static PhysicalWebBleClient getInstance(Application application) {
+        if (sInstance.get() == null) {
+            ChromeApplication chromeApplication = (ChromeApplication) application;
+            sInstance.compareAndSet(null, chromeApplication.createPhysicalWebBleClient());
+        }
+        return sInstance.get();
+    }
+
+    /**
+     * Begin subscribing to URLs broadcasted from BLE beacons.
+     * This currently does nothing and should be overridden by a subclass.
+     */
+    void subscribe() {
+        Log.d(TAG, "subscribing in empty client");
+    }
+}