Rewrite the Android implementation of BatteryMonitor directly in Java.

device/battery/android/java/src/org/chromium/device/battery/BatteryStatusManager.java

Index: device/battery/android/java/src/org/chromium/device/battery/BatteryStatusManager.java
diff --git a/device/battery/android/java/src/org/chromium/device/battery/BatteryStatusManager.java b/device/battery/android/java/src/org/chromium/device/battery/BatteryStatusManager.java
index 90c0f38f68bd9e590fa898cf3d53347fa00ef4ea..0601be1eb49afa5a3cb099f6e5e4f7ec1c4d5b51 100644
--- a/device/battery/android/java/src/org/chromium/device/battery/BatteryStatusManager.java
+++ b/device/battery/android/java/src/org/chromium/device/battery/BatteryStatusManager.java
@@ -12,20 +12,25 @@ import android.os.BatteryManager;
 import android.os.Build;
 import android.util.Log;
 
-import org.chromium.base.CalledByNative;
-import org.chromium.base.JNINamespace;
 import org.chromium.base.VisibleForTesting;
+import org.chromium.mojom.device.BatteryStatus;
 
 /**
- * Android implementation of the battery status APIs.
+ * Data source for battery status information. This class registers for battery status notifications
+ * from the system and calls the callback passed on construction whenever a notification is
+ * received.
  */
-@JNINamespace("device")
 class BatteryStatusManager {
 
     private static final String TAG = "BatteryStatusManager";
 
+    interface BatteryStatusCallback {
+        void onBatteryStatusChanged(BatteryStatus batteryStatus);
+    }
+
     // A reference to the application context in order to acquire the SensorService.
     private final Context mAppContext;
+    private final BatteryStatusCallback mCallback;
     private final IntentFilter mFilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
     private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
         @Override
@@ -34,50 +39,52 @@ class BatteryStatusManager {
         }
     };
 
-    // Non-zero if and only if we're listening for events.
-    // To avoid race conditions on the C++ side, access must be synchronized.
-    private long mNativePtr;
-    // The lock to access the mNativePtr.
-    private final Object mNativePtrLock = new Object();
+    // This is to workaround a Galaxy Nexus bug, see the comment in the constructor.
+    private final boolean mIgnoreBatteryPresentState;
 
     private boolean mEnabled = false;
 
-    protected BatteryStatusManager(Context context) {
+    private BatteryStatusManager(
+            Context context, BatteryStatusCallback callback, boolean ignoreBatteryPresentState) {
         mAppContext = context.getApplicationContext();
+        mCallback = callback;
+        mIgnoreBatteryPresentState = ignoreBatteryPresentState;
     }
 
-    @CalledByNative
-    static BatteryStatusManager getInstance(Context appContext) {
-        return new BatteryStatusManager(appContext);
+    BatteryStatusManager(Context context, BatteryStatusCallback callback) {
+        // BatteryManager.EXTRA_PRESENT appears to be unreliable on Galaxy Nexus,
+        // Android 4.2.1, it always reports false. See http://crbug.com/384348.
+        this(context, callback, Build.MODEL.equals("Galaxy Nexus"));
+    }
+
+    /**
+     * Creates a BatteryStatusManager without the Galaxy Nexus workaround for consistency in
+     * testing.
+     */
+    static BatteryStatusManager createBatteryStatusManagerForTesting(
+            Context context, BatteryStatusCallback callback) {
+        return new BatteryStatusManager(context, callback, false);
     }
 
     /**
-     * Start listening for intents
+     * Starts listening for intents.
      * @return True on success.
      */
-    @CalledByNative
-    boolean start(long nativePtr) {
-        synchronized (mNativePtrLock) {
-            if (!mEnabled && mAppContext.registerReceiver(mReceiver, mFilter) != null) {
-                // success
-                mNativePtr = nativePtr;
-                mEnabled = true;
-            }
+    boolean start() {
+        if (!mEnabled && mAppContext.registerReceiver(mReceiver, mFilter) != null) {
+            // success
+            mEnabled = true;
         }
         return mEnabled;
     }
 
     /**
-     * Stop listening to intents.
+     * Stops listening to intents.
      */
-    @CalledByNative
     void stop() {
-        synchronized (mNativePtrLock) {
-            if (mEnabled) {
-                mAppContext.unregisterReceiver(mReceiver);
-                mNativePtr = 0;
-                mEnabled = false;
-            }
+        if (mEnabled) {
+            mAppContext.unregisterReceiver(mReceiver);
+            mEnabled = false;
         }
     }
 
@@ -88,20 +95,17 @@ class BatteryStatusManager {
             return;
         }
 
-        boolean present = ignoreBatteryPresentState()
-                ? true : intent.getBooleanExtra(BatteryManager.EXTRA_PRESENT, false);
+        boolean present = mIgnoreBatteryPresentState
+                ? true
+                : intent.getBooleanExtra(BatteryManager.EXTRA_PRESENT, false);
         int pluggedStatus = intent.getIntExtra(BatteryManager.EXTRA_PLUGGED, -1);
 
         if (!present || pluggedStatus == -1) {
             // No battery or no plugged status: return default values.
-            gotBatteryStatus(true, 0, Double.POSITIVE_INFINITY, 1);
+            mCallback.onBatteryStatusChanged(new BatteryStatus());
             return;
         }
 
-        boolean charging = pluggedStatus != 0;
-        int status = intent.getIntExtra(BatteryManager.EXTRA_STATUS, -1);
-        boolean batteryFull = status == BatteryManager.BATTERY_STATUS_FULL;
-
         int current = intent.getIntExtra(BatteryManager.EXTRA_LEVEL, -1);
         int max = intent.getIntExtra(BatteryManager.EXTRA_SCALE, -1);
         double level = (double) current / (double) max;
@@ -114,35 +118,17 @@ class BatteryStatusManager {
         // we could compute it manually based on level delta.
         // TODO(timvolodine): add proper projection for chargingTime, dischargingTime
         // (see crbug.com/401553).
+        boolean charging = pluggedStatus != 0;
+        int status = intent.getIntExtra(BatteryManager.EXTRA_STATUS, -1);
+        boolean batteryFull = status == BatteryManager.BATTERY_STATUS_FULL;
         double chargingTime = (charging & batteryFull) ? 0 : Double.POSITIVE_INFINITY;
         double dischargingTime = Double.POSITIVE_INFINITY;
 
-        gotBatteryStatus(charging, chargingTime, dischargingTime, level);
-    }
-
-    /**
-     * Returns whether the BatteryStatusManager should ignore the battery present state.
-     * It is required for some devices that incorrectly set the EXTRA_PRESENT property.
-     */
-    protected boolean ignoreBatteryPresentState() {
-        // BatteryManager.EXTRA_PRESENT appears to be unreliable on Galaxy Nexus,
-        // Android 4.2.1, it always reports false. See crbug.com/384348.
-        return Build.MODEL.equals("Galaxy Nexus");
-    }
-
-    protected void gotBatteryStatus(boolean charging, double chargingTime,
-            double dischargingTime, double level) {
-        synchronized (mNativePtrLock) {
-            if (mNativePtr != 0) {
-                nativeGotBatteryStatus(mNativePtr, charging, chargingTime, dischargingTime, level);
-            }
-        }
+        BatteryStatus batteryStatus = new BatteryStatus();
+        batteryStatus.charging = charging;
+        batteryStatus.chargingTime = chargingTime;
+        batteryStatus.dischargingTime = dischargingTime;
+        batteryStatus.level = level;
+        mCallback.onBatteryStatusChanged(batteryStatus);
     }
-
-    /**
-     * Native JNI call
-     * see device/battery/battery_status_manager_android.cc
-     */
-    private native void nativeGotBatteryStatus(long nativeBatteryStatusManagerAndroid,
-            boolean charging, double chargingTime, double dischargingTime, double level);
 }