Stop using [Client=...] feature of Mojom for BatteryMonitor

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

Index: device/battery/android/java/src/org/chromium/device/battery/BatteryMonitorImpl.java
diff --git a/device/battery/android/java/src/org/chromium/device/battery/BatteryMonitorImpl.java b/device/battery/android/java/src/org/chromium/device/battery/BatteryMonitorImpl.java
index e44158912644a43af4c2c4aaeb1f88e6cd139517..364e21a88f8381ecab2d123c400e73d14ac428d8 100644
--- a/device/battery/android/java/src/org/chromium/device/battery/BatteryMonitorImpl.java
+++ b/device/battery/android/java/src/org/chromium/device/battery/BatteryMonitorImpl.java
@@ -7,7 +7,9 @@ package org.chromium.device.battery;
 import org.chromium.mojo.system.MojoException;
 import org.chromium.mojom.device.BatteryMonitor;
 import org.chromium.mojom.device.BatteryStatus;
-import org.chromium.mojom.device.BatteryStatusObserver;
+
+import java.util.ArrayList;
+import java.util.List;
 
 /**
  * Android implementation of the battery monitor service defined in
@@ -16,12 +18,15 @@ import org.chromium.mojom.device.BatteryStatusObserver;
 public class BatteryMonitorImpl implements BatteryMonitor {
     // Factory that created this instance and notifies it about battery status changes.
     private final BatteryMonitorFactory mFactory;
+    private final List<QueryNextStatusResponse> mCallbacks;
+    private BatteryStatus mStatus;
+    private boolean mHasStatusToReport;
     private boolean mSubscribed;
 
-    private BatteryStatusObserver mClient;
-
     public BatteryMonitorImpl(BatteryMonitorFactory batteryMonitorFactory) {
         mFactory = batteryMonitorFactory;
+        mCallbacks = new ArrayList<QueryNextStatusResponse>();
+        mHasStatusToReport = false;
         mSubscribed = true;
     }
 
@@ -33,11 +38,6 @@ public class BatteryMonitorImpl implements BatteryMonitor {
     }
 
     @Override
-    public void setClient(BatteryStatusObserver client) {
-        mClient = client;
-    }
-
-    @Override
     public void close() {
         unsubscribe();
     }
@@ -47,12 +47,29 @@ public class BatteryMonitorImpl implements BatteryMonitor {
         unsubscribe();
     }
 
-    /**
-     * Notifies the client passing the given battery status information.
-     */
+    @Override
+    public void queryNextStatus(QueryNextStatusResponse callback) {
+        mCallbacks.add(callback);
+
+        if (mHasStatusToReport) {
+            reportStatus();
+        }
+    }
+
     void didChange(BatteryStatus batteryStatus) {
-        if (mClient != null) {
-            mClient.didChange(batteryStatus);
+        mStatus = batteryStatus;
+        mHasStatusToReport = true;
+
+        if (!mCallbacks.isEmpty()) {
+            reportStatus();
         }
-    };
+    }
+
+    void reportStatus() {
+        for (QueryNextStatusResponse callback : mCallbacks) {
+            callback.call(mStatus);
+        }
+        mCallbacks.clear();
+        mHasStatusToReport = false;
+    }
 }