Reland Pull the Activity context from WindowAndroid if possible

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.annotation.TargetApi;
 import android.app.Activity;
 import android.app.PendingIntent;
 import android.content.ContentResolver;
 import android.content.Context;
+import android.content.ContextWrapper;
 import android.content.Intent;
 import android.content.pm.PackageManager;
 import android.os.Build;
 import android.os.Bundle;
 import android.os.Process;
 import android.util.Log;
 import android.util.SparseArray;
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.accessibility.AccessibilityManager;
@@ skipping 93 matching lines @@
         public void onVSync(VSyncMonitor monitor, long vsyncTimeMicros) {
             if (mNativeWindowAndroid != 0) {
                 nativeOnVSync(mNativeWindowAndroid,
                               vsyncTimeMicros,
                               mVSyncMonitor.getVSyncPeriodInMicroseconds());
             }
         }
     };
 
     /**
+     * Extract the activity if the given Context either is or wraps one.
+     * Only retrieve the base context if the supplied context is a {@link ContextWrapper} but not
+     * an Activity, given that Activity is already a subclass of ContextWrapper.
+     * @param context The context to check.
+     * @return The {@link Activity} that is extracted through the given Context.
+     */
+    public static Activity activityFromContext(Context context) {
+        if (context instanceof Activity) {
+            return ((Activity) context);
+        } else if (context instanceof ContextWrapper) {
+            context = ((ContextWrapper) context).getBaseContext();
+            return activityFromContext(context);
+        } else {
+            return null;
+        }
+    }
+
+    /**
      * @return true if onVSync handler is executing.
      *
      * @see org.chromium.ui.VSyncMonitor#isInsideVSync()
      */
     public boolean isInsideVSync() {
         return mVSyncMonitor.isInsideVSync();
     }
 
     /**
      * @param context The application context.
@@ skipping 480 matching lines @@
     private native long nativeInit();
     private native void nativeOnVSync(long nativeWindowAndroid,
                                       long vsyncTimeMicros,
                                       long vsyncPeriodMicros);
     private native void nativeOnVisibilityChanged(long nativeWindowAndroid, boolean visible);
     private native void nativeOnActivityStopped(long nativeWindowAndroid);
     private native void nativeOnActivityStarted(long nativeWindowAndroid);
     private native void nativeDestroy(long nativeWindowAndroid);
 
 }