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

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

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.ui.base;
 
 import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
 import android.annotation.SuppressLint;
 import android.app.Activity;
@@ skipping 218 matching lines @@
 
         Object errors = bundle.getSerializable(WINDOW_CALLBACK_ERRORS);
         if (errors instanceof HashMap) {
             @SuppressWarnings("unchecked")
             HashMap<Integer, String> intentErrors = (HashMap<Integer, String>) errors;
             mIntentErrors = intentErrors;
         }
     }
 
     /**
+     * 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.
      * @param data The data returned by the intent.
      * @return Boolean value of whether the intent was started by the native window.
      */
     public boolean onActivityResult(int requestCode, int resultCode, Intent data) {
         return false;
     }
 
@@ skipping 96 matching lines @@
                     mAnimationPlaceholderView.setWillNotDraw(true);
                 }
             }
         });
     }
 
     private native long nativeInit();
     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);
 
 }