Factor out RenderWidgetHostConnector

content/browser/android/render_widget_host_connector.h

+// 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.
+
+#ifndef CONTENT_BROWSER_ANDROID_RENDER_WIDGET_HOST_CONNECTOR_H_
+#define CONTENT_BROWSER_ANDROID_RENDER_WIDGET_HOST_CONNECTOR_H_
+
+#include "base/memory/weak_ptr.h"
+#include "content/browser/renderer_host/render_widget_host_view_android.h"
+#include "content/public/browser/web_contents_observer.h"
+
+namespace content {
+
+// A base class used to connect an object of the content layer lifecycle
+// to |RenderWidgetHostViewAndroid|. The inherting class needs to
+// override |UpdateRenderProcessConnection| to set itself to the RWHVA
+// brought up foreground, and null out its reference in the RWHVA going
+// away so it won't access the object any more.
+// This class owns itself and gets deleted when WebContents is deleted.
+class RenderWidgetHostConnector {
+ public:
+  explicit RenderWidgetHostConnector(WebContents* web_contents);
+  virtual ~RenderWidgetHostConnector();
+
+  // Method to set itself to the |new_rwhva|, and null out the reference
+  // in |old_rwvha|. Example:
+  //
+  // if (old_rwhva)
+  //   old_rwhva->set_object(nullptr);
+  // if (new_rwhva)
+  //   new_rwhva->set_object(this);
+  virtual void UpdateRenderProcessConnection(
+      RenderWidgetHostViewAndroid* old_rwhva,
+      RenderWidgetHostViewAndroid* new_rhwva) = 0;
+
+  RenderWidgetHostViewAndroid* GetRWHVAForTesting() const;
+
+ private:
+  class Observer;
+  std::unique_ptr<Observer> render_widget_observer_;
+
+  DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostConnector);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_ANDROID_RENDER_WIDGET_HOST_CONNECTOR_H_