Extract base class from AtomRendererClient

The new `RendererClientBase` class contains code that is not specific to node.js
integration with the renderer.

atom/renderer/renderer_client_base.h

@@ -0,0 +1,50 @@
+// Copyright (c) 2017 GitHub, Inc.
+// Use of this source code is governed by the MIT license that can be
+// found in the LICENSE file.
+
+#ifndef ATOM_RENDERER_RENDERER_CLIENT_BASE_H_
+#define ATOM_RENDERER_RENDERER_CLIENT_BASE_H_
+
+#include <string>
+#include <vector>
+
+#include "content/public/renderer/content_renderer_client.h"
+
+namespace atom {
+
+class PreferencesManager;
+
+class RendererClientBase : public content::ContentRendererClient {
+ public:
+  RendererClientBase();
+  virtual ~RendererClientBase();
+
+ protected:
+  void AddRenderBindings(v8::Isolate* isolate,
+                         v8::Local<v8::Object> binding_object);
+
+  // content::ContentRendererClient:
+  void RenderThreadStarted() override;
+  void RenderFrameCreated(content::RenderFrame*) override;
+  void RenderViewCreated(content::RenderView*) override;
+  blink::WebSpeechSynthesizer* OverrideSpeechSynthesizer(
+      blink::WebSpeechSynthesizerClient* client) override;
+  bool OverrideCreatePlugin(content::RenderFrame* render_frame,
+                            blink::WebLocalFrame* frame,
+                            const blink::WebPluginParams& params,
+                            blink::WebPlugin** plugin) override;
+  content::BrowserPluginDelegate* CreateBrowserPluginDelegate(
+      content::RenderFrame* render_frame,
+      const std::string& mime_type,
+      const GURL& original_url) override;
+  void AddSupportedKeySystems(
+      std::vector<std::unique_ptr<::media::KeySystemProperties>>* key_systems)
+      override;
+
+ private:
+  std::unique_ptr<PreferencesManager> preferences_manager_;
+};
+
+}  // namespace atom
+
+#endif  // ATOM_RENDERER_RENDERER_CLIENT_BASE_H_