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

chrome/android/java/src/org/chromium/chrome/browser/Tab.java

Index: chrome/android/java/src/org/chromium/chrome/browser/Tab.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/Tab.java b/chrome/android/java/src/org/chromium/chrome/browser/Tab.java
index 5bf6328450c9af1a5091fc58dadf55735127b168..210119e5b7e51c010a19befbdfc93746d3929bde 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/Tab.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/Tab.java
@@ -1181,6 +1181,13 @@
     }
 
     /**
+     * Called on the foreground tab when the Activity is stopped.
+     */
+    public void onActivityStop() {
+        hide();
+    }
+
+    /**
      * Prepares the tab to be shown. This method is supposed to be called before the tab is
      * displayed. It restores the ContentView if it is not available after the cold start and
      * reloads the tab if its renderer has crashed.