bluetooth: android: Initial Low Energy Discovery Sessions.

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 5775b0073f0a72dc4c815a1db2f0d511c183baf9..a29c9d8c2515d0af3f7709e50ec581becd3218f2 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
@@ -4,30 +4,46 @@
 
 package org.chromium.device.bluetooth;
 
+import android.annotation.TargetApi;
 import android.bluetooth.BluetoothAdapter;
+import android.bluetooth.le.ScanSettings;
+import android.os.Build;
 
 import org.chromium.base.CalledByNative;
 import org.chromium.base.JNINamespace;
 import org.chromium.base.Log;
 
+import java.util.List;
+
 /**
  * Exposes android.bluetooth.BluetoothAdapter as necessary for C++
  * device::BluetoothAdapterAndroid, which implements the cross platform
  * device::BluetoothAdapter.
  */
 @JNINamespace("device")
+@TargetApi(Build.VERSION_CODES.LOLLIPOP)
 final class ChromeBluetoothAdapter {
     private static final String TAG = "cr.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.
      */
-    private ChromeBluetoothAdapter(Wrappers.BluetoothAdapterWrapper adapterWrapper) {
+    public ChromeBluetoothAdapter(
+            long nativeBluetoothAdapterAndroid, Wrappers.BluetoothAdapterWrapper adapterWrapper) {
+        mNativeBluetoothAdapterAndroid = nativeBluetoothAdapterAndroid;
         mAdapter = adapterWrapper;
         if (adapterWrapper == null) {
             Log.i(TAG, "ChromeBluetoothAdapter created with no adapterWrapper.");
@@ -36,6 +52,15 @@ final class ChromeBluetoothAdapter {
         }
     }
 
+    /**
+     * Handles C++ object being destroyed.
+     */
+    @CalledByNative
+    private void onBluetoothAdapterAndroidDestruction() {
+        stopScan();
+        mNativeBluetoothAdapterAndroid = 0;
+    }
+
     // ---------------------------------------------------------------------------------------------
     // BluetoothAdapterAndroid methods implemented in java:
 
@@ -43,8 +68,10 @@ final class ChromeBluetoothAdapter {
     // 'Object' type must be used because inner class Wrappers.BluetoothAdapterWrapper reference is
     // not handled by jni_generator.py JavaToJni. http://crbug.com/505554
     @CalledByNative
-    public static ChromeBluetoothAdapter create(Object adapterWrapper) {
-        return new ChromeBluetoothAdapter((Wrappers.BluetoothAdapterWrapper) adapterWrapper);
+    private static ChromeBluetoothAdapter create(
+            long nativeBluetoothAdapterAndroid, Object adapterWrapper) {
+        return new ChromeBluetoothAdapter(
+                nativeBluetoothAdapterAndroid, (Wrappers.BluetoothAdapterWrapper) adapterWrapper);
     }
 
     // Implements BluetoothAdapterAndroid::GetAddress.
@@ -89,6 +116,120 @@ final class ChromeBluetoothAdapter {
     // Implements BluetoothAdapterAndroid::IsDiscovering.
     @CalledByNative
     private boolean isDiscovering() {
-        return isPresent() && mAdapter.isDiscovering();
+        return isPresent() && (mAdapter.isDiscovering() || mScanCallback != null);
+    }
+
+    // Implements BluetoothAdapterAndroid::AddDiscoverySession.
+    @CalledByNative
+    private boolean addDiscoverySession() {
+        if (!isPowered()) {
+            Log.d(TAG, "addDiscoverySession: Fails: !isPowered");
+            return false;
+        }
+
+        mNumDiscoverySessions++;
+        Log.d(TAG, "addDiscoverySession: Now %d sessions.", mNumDiscoverySessions);
+        if (mNumDiscoverySessions > 1) {
+            return true;
+        }
+
+        if (!startScan()) {
+            mNumDiscoverySessions--;
+            return false;
+        }
+        return true;
     }
+
+    // Implements BluetoothAdapterAndroid::RemoveDiscoverySession.
+    @CalledByNative
+    private boolean removeDiscoverySession() {
+        if (mNumDiscoverySessions == 0) {
+            assert false;
+            Log.w(TAG, "removeDiscoverySession: No scan in progress.");
+            return false;
+        }
+
+        --mNumDiscoverySessions;
+
+        if (mNumDiscoverySessions == 0) {
+            Log.d(TAG, "removeDiscoverySession: Now 0 sessions. Stopping scan.");
+            return stopScan();
+        }
+
+        Log.d(TAG, "removeDiscoverySession: Now %d sessions.", mNumDiscoverySessions);
+        return true;
+    }
+
+    // ---------------------------------------------------------------------------------------------
+    // Implementation details:
+
+    /**
+     * Starts a Low Energy scan.
+     * @return True on success.
+     */
+    private boolean startScan() {
+        // scanMode note: SCAN_FAILED_FEATURE_UNSUPPORTED is caused (at least on some devices) if
+        // setReportDelay() is used or if SCAN_MODE_LOW_LATENCY isn't used.
+        int scanMode = ScanSettings.SCAN_MODE_LOW_LATENCY;
+
+        assert mScanCallback == null;
+        mScanCallback = new ScanCallback();
+
+        try {
+            mAdapter.getBluetoothLeScanner().startScan(null /* filters */, scanMode, mScanCallback);
+        } catch (IllegalArgumentException e) {
+            Log.e(TAG, "Cannot start scan: " + e);
+            return false;
+        }
+        return true;
+    }
+
+    /**
+     * Stops the Low Energy scan.
+     * @return True if a scan was in progress.
+     */
+    private boolean stopScan() {
+        if (mScanCallback == null) {
+            return false;
+        }
+        try {
+            mAdapter.getBluetoothLeScanner().stopScan(mScanCallback);
+        } catch (IllegalArgumentException e) {
+            Log.e(TAG, "Cannot stop scan: " + e);
+            mScanCallback = null;
+            return false;
+        }
+        mScanCallback = null;
+        return true;
+    }
+
+    /**
+     * Implements callbacks used during a Low Energy scan by notifying upon
+     * devices discovered or detecting a scan failure.
+     */
+    private class ScanCallback extends Wrappers.ScanCallbackWrapper {
+        @Override
+        public void onBatchScanResult(List<Wrappers.ScanResultWrapper> results) {
+            Log.v(TAG, "onBatchScanResults");
+        }
+
+        @Override
+        public void onScanResult(int callbackType, Wrappers.ScanResultWrapper result) {
+            Log.v(TAG, "onScanResult %d %s %s", callbackType, result.getDevice().getAddress(),
+                    result.getDevice().getName());
+        }
+
+        @Override
+        public void onScanFailed(int errorCode) {
+            Log.w(TAG, "onScanFailed: %d", errorCode);
+            nativeOnScanFailed(mNativeBluetoothAdapterAndroid);
+            mNumDiscoverySessions = 0;
+        }
+    }
+
+    // ---------------------------------------------------------------------------------------------
+    // BluetoothAdapterAndroid C++ methods declared for access from java:
+
+    // Binds to BluetoothAdapterAndroid::OnScanFailed.
+    private native void nativeOnScanFailed(long nativeBluetoothAdapterAndroid);
 }