Make PaymentRequestImpl work with RenderFrameHost

content/public/android/java/src/org/chromium/content_public/browser/WebContentsStatics.java

+// Copyright 2017 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.content_public.browser;
+
+import org.chromium.content.browser.framehost.RenderFrameHostDelegate;
+import org.chromium.content.browser.framehost.RenderFrameHostImpl;
+
+/**
+ * Static public methods for WebContents.
+ */
+public class WebContentsStatics {
+    /**
+     * @return The WebContens associated witht the RenderFrameHost. This can be null.
+     */
+    public static WebContents fromRenderFrameHost(RenderFrameHost rfh) {
+        RenderFrameHostDelegate delegate = ((RenderFrameHostImpl) rfh).getRenderFrameHostDelegate();
+        if (delegate == null || !(delegate instanceof WebContents)) {
+            return null;
+        }
+        return (WebContents) delegate;
+    }
+}