Pull the Activity context from WindowAndroid if possible

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 3d775de11c9f19e5be9260380f87fbb609a9f2fa..3d941a3ecc003487b835e5e693d4290e553490d8 100644
--- a/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
+++ b/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
@@ -12,6 +12,7 @@ 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;
@@ -123,6 +124,24 @@ public class WindowAndroid {
     };
 
     /**
+     * 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()