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

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

Index: device/bluetooth/android/java/src/org/chromium/device/bluetooth/ChromeBluetoothAdapter.java
diff --git a/device/bluetooth/android/java/src/org/chromium/device/bluetooth/ChromeBluetoothAdapter.java b/device/bluetooth/android/java/src/org/chromium/device/bluetooth/ChromeBluetoothAdapter.java
index 0a54a0bdfe73f817a2cff9c0ee24783c91842eed..54a8eb926768ad12f3994c9df4baec9adf93ea09 100644
--- a/device/bluetooth/android/java/src/org/chromium/device/bluetooth/ChromeBluetoothAdapter.java
+++ b/device/bluetooth/android/java/src/org/chromium/device/bluetooth/ChromeBluetoothAdapter.java
@@ -8,6 +8,10 @@ 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;
 
@@ -26,7 +30,7 @@ import java.util.List;
  */
 @JNINamespace("device")
 @TargetApi(Build.VERSION_CODES.LOLLIPOP)
-final class ChromeBluetoothAdapter {
+final class ChromeBluetoothAdapter extends BroadcastReceiver {
     private static final String TAG = "Bluetooth";
 
     private long mNativeBluetoothAdapterAndroid;
@@ -49,6 +53,7 @@ final class ChromeBluetoothAdapter {
             long nativeBluetoothAdapterAndroid, Wrappers.BluetoothAdapterWrapper adapterWrapper) {
         mNativeBluetoothAdapterAndroid = nativeBluetoothAdapterAndroid;
         mAdapter = adapterWrapper;
+        registerBroadcastReceiver();
         if (adapterWrapper == null) {
             Log.i(TAG, "ChromeBluetoothAdapter created with no adapterWrapper.");
         } else {
@@ -63,6 +68,7 @@ final class ChromeBluetoothAdapter {
     private void onBluetoothAdapterAndroidDestruction() {
         stopScan();
         mNativeBluetoothAdapterAndroid = 0;
+        unregisterBroadcastReceiver();
     }
 
     // ---------------------------------------------------------------------------------------------
@@ -187,6 +193,19 @@ final class ChromeBluetoothAdapter {
                 || 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.
@@ -275,6 +294,45 @@ final class ChromeBluetoothAdapter {
         }
     }
 
+    @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:
 
@@ -287,4 +345,8 @@ final class ChromeBluetoothAdapter {
     // 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);
 }