Factor DRP PreviewsState logic out of content

components/data_reduction_proxy/content/renderer/content_previews_render_frame_observer.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 COMPONENTS_DATA_REDUCTION_PROXY_CONTENT_RENDERER_CONTENT_PREVIEWS_RENDER_FRAME_OBSERVER_H_
+#define COMPONENTS_DATA_REDUCTION_PROXY_CONTENT_RENDERER_CONTENT_PREVIEWS_RENDER_FRAME_OBSERVER_H_
+
+#include "base/macros.h"
+#include "content/public/common/previews_state.h"
+#include "content/public/renderer/render_frame_observer.h"
+#include "third_party/WebKit/public/platform/WebURLResponse.h"
+
+namespace data_reduction_proxy {
+
+class ContentPreviewsRenderFrameObserver : public content::RenderFrameObserver {

[Charlie Reis, 2017/07/06 20:12:21]

Can you add a comment about lifetime and who owns instances of this class? 
(Looks like the class deletes itself when the RenderFrame it is observing goes
away?)

[megjablon, 2017/07/10 17:38:08]

Done.

+ public:
+  ContentPreviewsRenderFrameObserver(content::RenderFrame* render_frame);
+  ~ContentPreviewsRenderFrameObserver() override;
+
+  static content::PreviewsState GetPreviewsStateFromResponse(
+      content::PreviewsState original_state,
+      const blink::WebURLResponse& web_url_response);
+
+ private:
+  // content::RenderFrameObserver:
+  void OnDestruct() override;
+  void DidCommitProvisionalLoad(bool is_new_navigation,
+                                bool is_same_document_navigation) override;
+
+  DISALLOW_COPY_AND_ASSIGN(ContentPreviewsRenderFrameObserver);
+};
+
+}  // namespace data_reduction_proxy
+#endif  // COMPONENTS_DATA_REDUCTION_PROXY_CONTENT_RENDERER_CONTENT_PREVIEWS_RENDER_FRAME_OBSERVER_H_