[Android] Stop hiding the RWHV layer subtree when hiding the widget

ui/android/java/src/org/chromium/ui/base/WindowAndroid.java

Index: ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
diff --git a/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java b/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
index 60d6c9c3fb69551b444808e8eb51af0b7c1a529b..5bd2c8a1e0f86348c67a13076becb3710c33068e 100644
--- a/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
+++ b/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
@@ -251,6 +251,24 @@ public class WindowAndroid {
     }
 
     /**
+     * For window instances associated with an activity, notifies any listeners
+     * that the activity has been paused.
+     */
+    protected void onActivityPaused() {
+        if (mNativeWindowAndroid == 0) return;
+        nativeOnActivityPaused(mNativeWindowAndroid);
+    }
+
+    /**
+     * For window instances associated with an activity, notifies any listeners
+     * that the activity has been paused.
+     */
+    protected void onActivityResumed() {
+        if (mNativeWindowAndroid == 0) return;
+        nativeOnActivityResumed(mNativeWindowAndroid);
+    }
+
+    /**
      * Responds to the intent result if the intent was created by the native window.
      * @param requestCode Request code of the requested intent.
      * @param resultCode Result code of the requested intent.
@@ -414,6 +432,8 @@ public class WindowAndroid {
     private native void nativeOnVSync(long nativeWindowAndroid,
                                       long vsyncTimeMicros,
                                       long vsyncPeriodMicros);
+    private native void nativeOnActivityPaused(long nativeWindowAndroid);
+    private native void nativeOnActivityResumed(long nativeWindowAndroid);
     private native void nativeDestroy(long nativeWindowAndroid);
 
 }