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;
     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);
+        }
+    }
+
     /**
      * 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, "BluetoothStateReceiver#onReceive action: %d", state);

[scheib, 2016/02/26 00:05:59]

This string doesn't mean much to me, would it be more direct as
"onReceive: BluetoothAdapter.ACTION_STATE_CHANGED: %d"
Would be nice to output string values for the 4 state values too, but that's
optional.

[perja, 2016/02/26 10:51:04]

Done.

+
+            switch (state) {
+                case BluetoothAdapter.STATE_ON:
+                    nativeOnAdapterStateChanged(mNativeBluetoothAdapterAndroid, true);
+                    break;
+                case BluetoothAdapter.STATE_OFF:
+                    nativeOnAdapterStateChanged(mNativeBluetoothAdapterAndroid, false);
+                    break;
+                default:
+                    // do nothing
+            }
+        }
+    }
+
     // ---------------------------------------------------------------------------------------------
     // 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);
 }