Fire SystemMonitor::{RESUME,SUSPEND}_EVENT on Android.

base/android/java/src/org/chromium/base/SystemMonitor.java

Index: base/android/java/src/org/chromium/base/SystemMonitor.java
diff --git a/base/android/java/src/org/chromium/base/SystemMonitor.java b/base/android/java/src/org/chromium/base/SystemMonitor.java
index f43f115be1274a66bdd72a8e7e9183c7680cf59b..30f61a6ea86cad352b3ea6e2f788a7488bac2d35 100644
--- a/base/android/java/src/org/chromium/base/SystemMonitor.java
+++ b/base/android/java/src/org/chromium/base/SystemMonitor.java
@@ -4,10 +4,12 @@
 
 package org.chromium.base;
 
+import android.app.Activity;
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.os.BatteryManager;
+import android.os.Handler;
 import android.os.Looper;
 
 
@@ -15,22 +17,35 @@ import android.os.Looper;
  * Integrates native SystemMonitor with the java side.
  */
 @JNINamespace("base::android")
-public class SystemMonitor {
+public class SystemMonitor implements ActivityStatus.StateListener {
+    private static final long SUSPEND_DELAY_MS = 1 * 60 * 1000;  // 1 minute.
     private static SystemMonitor sInstance;
 
     private boolean mIsBatteryPower;
+    private final Handler mHandler = new Handler(Looper.getMainLooper());
+
+    // Asynchronous task used to fire the "paused" event to the native side 1 minute after the main
+    // activity transitioned to the "paused" state. This event is not sent immediately because it
+    // would be too aggressive. An Android activity can be in the "paused" state quite often. This
+    // can happen when a dialog window shows up for instance.
+    private static final Runnable sSuspendTask = new Runnable() {
+            @Override
+            public void run() {
+                nativeOnMainActivitySuspended();
+            }
+        };
 
     public static void createForTests(Context context) {
-        // Applications will create this once the
-        // JNI side has been fully wired up both sides.
-        // For tests, we just need native -> java, that is,
-        // we don't need to notify java -> native on creation.
+        // Applications will create this once the JNI side has been fully wired up both sides. For
+        // tests, we just need native -> java, that is, we don't need to notify java -> native on
+        // creation.
         sInstance = new SystemMonitor();
     }
 
     public static void create(Context context) {
         if (sInstance == null) {
             sInstance = new SystemMonitor();
+            ActivityStatus.registerStateListener(sInstance);
             IntentFilter ifilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
             Intent batteryStatusIntent = context.registerReceiver(null, ifilter);
             onBatteryChargingChanged(batteryStatusIntent);
@@ -42,9 +57,8 @@ public class SystemMonitor {
 
     public static void onBatteryChargingChanged(Intent intent) {
         if (sInstance == null) {
-            // We may be called by the framework intent-filter before being
-            // fully initialized. This is not a problem, since our constructor
-            // will check for the state later on.
+            // We may be called by the framework intent-filter before being fully initialized. This
+            // is not a problem, since our constructor will check for the state later on.
             return;
         }
         int chargePlug = intent.getIntExtra(BatteryManager.EXTRA_PLUGGED, -1);
@@ -54,11 +68,23 @@ public class SystemMonitor {
         nativeOnBatteryChargingChanged();
     }
 
+    @Override
+    public void onActivityStateChange(int newState) {
+        if (newState == ActivityStatus.RESUMED) {
+            // Remove the callback from the message loop in case it hasn't been executed yet.
+            mHandler.removeCallbacks(sSuspendTask);
+            nativeOnMainActivityResumed();
+        } else if (newState == ActivityStatus.PAUSED) {
+            mHandler.postDelayed(sSuspendTask, SUSPEND_DELAY_MS);
+        }
+    }
+
     @CalledByNative
     private static boolean isBatteryPower() {
         return sInstance.mIsBatteryPower;
     }
 
     private static native void nativeOnBatteryChargingChanged();
-
+    private static native void nativeOnMainActivitySuspended();
+    private static native void nativeOnMainActivityResumed();
 }