bluetooth: android: register for adapter on/off events.

device/bluetooth/android/java/src/org/chromium/device/bluetooth/ChromeBluetoothAdapter.java

 // 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.device.bluetooth;
 
 import android.Manifest;
 import android.annotation.TargetApi;
 import android.bluetooth.BluetoothAdapter;
 import android.bluetooth.le.ScanSettings;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
 import android.os.Build;
 import android.os.ParcelUuid;
 
 import org.chromium.base.Log;
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.base.annotations.JNINamespace;
 
 import java.util.List;
 
 /**
  * Exposes android.bluetooth.BluetoothAdapter as necessary for C++
  * device::BluetoothAdapterAndroid, which implements the cross platform
  * device::BluetoothAdapter.
  *
  * Lifetime is controlled by device::BluetoothAdapterAndroid.
  */
 @JNINamespace("device")
 @TargetApi(Build.VERSION_CODES.LOLLIPOP)
-final class ChromeBluetoothAdapter {
+final class ChromeBluetoothAdapter extends BroadcastReceiver {
     private static final String TAG = "Bluetooth";
 
     private long mNativeBluetoothAdapterAndroid;
     private Wrappers.BluetoothAdapterWrapper mAdapter;

[Ted C, 2016/02/26 17:50:35]

can you mark this final?

[scheib, 2016/02/26 20:23:47]

Done.

     private int mNumDiscoverySessions;
     private ScanCallback mScanCallback;
 
     // ---------------------------------------------------------------------------------------------
     // Construction and handler for C++ object destruction.
 
     /**
      * Constructs a ChromeBluetoothAdapter.
      * @param nativeBluetoothAdapterAndroid Is the associated C++
      *                                      BluetoothAdapterAndroid pointer value.
      * @param adapterWrapper Wraps the default android.bluetooth.BluetoothAdapter,
      *                       but may be either null if an adapter is not available
      *                       or a fake for testing.
      */
     public ChromeBluetoothAdapter(
             long nativeBluetoothAdapterAndroid, Wrappers.BluetoothAdapterWrapper adapterWrapper) {
         mNativeBluetoothAdapterAndroid = nativeBluetoothAdapterAndroid;
         mAdapter = adapterWrapper;
+        registerBroadcastReceiver();
         if (adapterWrapper == null) {
             Log.i(TAG, "ChromeBluetoothAdapter created with no adapterWrapper.");
         } else {
             Log.i(TAG, "ChromeBluetoothAdapter created with provided adapterWrapper.");
         }
     }
 
     /**
      * Handles C++ object being destroyed.
      */
     @CalledByNative
     private void onBluetoothAdapterAndroidDestruction() {
         stopScan();
         mNativeBluetoothAdapterAndroid = 0;
+        unregisterBroadcastReceiver();
     }
 
     // ---------------------------------------------------------------------------------------------
     // BluetoothAdapterAndroid methods implemented in java:
 
     // Implements BluetoothAdapterAndroid::Create.
     // 'Object' type must be used for |adapterWrapper| because inner class
     // Wrappers.BluetoothAdapterWrapper reference is not handled by jni_generator.py JavaToJni.
     // http://crbug.com/505554
     @CalledByNative
@@ skipping 104 matching lines @@
 
     /**
      * @return true if Chromium has permission to scan for Bluetooth devices.
      */
     private boolean canScan() {
         Wrappers.ContextWrapper context = mAdapter.getContext();
         return context.checkPermission(Manifest.permission.ACCESS_COARSE_LOCATION)
                 || context.checkPermission(Manifest.permission.ACCESS_FINE_LOCATION);
     }
 
+    private void registerBroadcastReceiver() {
+        if (mAdapter != null) {
+            mAdapter.getContext().registerReceiver(
+                    this, new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED));
+        }
+    }
+
+    private void unregisterBroadcastReceiver() {
+        if (mAdapter != null) {
+            mAdapter.getContext().unregisterReceiver(this);

[Ted C, 2016/02/26 17:50:35]

my comment about marking the adapter final is to ensure the null-ness of it can
not change.  We want to make sure we are unregistering the receiver so we can't
have something setting it to null and having this be incorrectly skipped.

[scheib, 2016/02/26 20:23:47]

Acknowledged.

+        }
+    }
+
     /**
      * Starts a Low Energy scan.
      * @return True on success.
      */
     private boolean startScan() {
         Wrappers.BluetoothLeScannerWrapper scanner = mAdapter.getBluetoothLeScanner();
 
         if (scanner == null) {
             return false;
         }
@@ skipping 68 matching lines @@
         }
 
         @Override
         public void onScanFailed(int errorCode) {
             Log.w(TAG, "onScanFailed: %d", errorCode);
             nativeOnScanFailed(mNativeBluetoothAdapterAndroid);
             mNumDiscoverySessions = 0;
         }
     }
 
+    @Override
+    public void onReceive(Context context, Intent intent) {
+        String action = intent.getAction();
+
+        if (isPresent() && BluetoothAdapter.ACTION_STATE_CHANGED.equals(action)) {
+            int state = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, BluetoothAdapter.ERROR);
+
+            Log.w(TAG, "onReceive: BluetoothAdapter.ACTION_STATE_CHANGED: %s",
+                    getBluetoothStateString(state));
+
+            switch (state) {
+                case BluetoothAdapter.STATE_ON:
+                    nativeOnAdapterStateChanged(mNativeBluetoothAdapterAndroid, true);
+                    break;
+                case BluetoothAdapter.STATE_OFF:
+                    nativeOnAdapterStateChanged(mNativeBluetoothAdapterAndroid, false);
+                    break;
+                default:
+                    // do nothing
+            }
+        }
+    }
+
+    private String getBluetoothStateString(int state) {
+        switch (state) {
+            case BluetoothAdapter.STATE_OFF:
+                return "STATE_OFF";
+            case BluetoothAdapter.STATE_ON:
+                return "STATE_ON";
+            case BluetoothAdapter.STATE_TURNING_OFF:
+                return "STATE_TURNING_OFF";
+            case BluetoothAdapter.STATE_TURNING_ON:
+                return "STATE_TURNING_ON";
+            default:
+                assert false;
+                return "illegal state: " + state;
+        }
+    }
+
     // ---------------------------------------------------------------------------------------------
     // BluetoothAdapterAndroid C++ methods declared for access from java:
 
     // Binds to BluetoothAdapterAndroid::OnScanFailed.
     private native void nativeOnScanFailed(long nativeBluetoothAdapterAndroid);
 
     // Binds to BluetoothAdapterAndroid::CreateOrUpdateDeviceOnScan.
     // 'Object' type must be used for |bluetoothDeviceWrapper| because inner class
     // Wrappers.BluetoothDeviceWrapper reference is not handled by jni_generator.py JavaToJni.
     // http://crbug.com/505554
     private native void nativeCreateOrUpdateDeviceOnScan(long nativeBluetoothAdapterAndroid,
             String address, Object bluetoothDeviceWrapper, List<ParcelUuid> advertisedUuids);
+
+    // Binds to BluetoothAdapterAndroid::nativeOnAdapterStateChanged
+    private native void nativeOnAdapterStateChanged(
+            long nativeBluetoothAdapterAndroid, boolean powered);
 }