extensions/browser/guest_view/mime_handler_view/mime_handler_view_attach_helper.h

// Copyright 2019 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 EXTENSIONS_BROWSER_GUEST_VIEW_MIME_HANDLER_VIEW_MIME_HANDLER_VIEW_ATTACH_HELPER_H_
#define EXTENSIONS_BROWSER_GUEST_VIEW_MIME_HANDLER_VIEW_MIME_HANDLER_VIEW_ATTACH_HELPER_H_

#include <stdint.h>

#include <map>
#include <string>

#include "base/bind_helpers.h"
#include "base/containers/flat_map.h"
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "content/public/browser/render_process_host_observer.h"
#include "extensions/common/mojom/guest_view.mojom.h"

namespace content {
class RenderFrameHost;
class RenderProcessHost;
class WebContents;
}  // namespace content

namespace extensions {

class MimeHandlerViewGuest;

// Helper class for attaching a MimeHandlerViewGuest to its outer WebContents.
// This class is exclusively used for frame-based MimeHandlerView. There is one
// instance of this class per process. All the associated state in this class
// is accessed on UI thread.
class MimeHandlerViewAttachHelper : content::RenderProcessHostObserver {
 public:
  // Returns the unique helper for process identified with |render_process_id|.
  static MimeHandlerViewAttachHelper* Get(int render_process_id);

  // Called on IO thread to give this class a chance to override the response
  // body for frame-based MimeHandlerView. |payload| will be populated with a
  // template HTML page which appends a child frame to the frame associated
  // with |navigating_frame_tree_node_id|. Then, an observer of the associated
  // WebContents will observe the newly created RenderFrameHosts. As soon the
  // expected RFH (i.e., the one added by the HTML string) is found, the
  // renderer is notified to start the MimHandlerView creation process. The
  // mentioned child frame will be used to attach the GuestView's WebContents to
  // the outer WebContents (WebContents associated with
  // |navigating_frame_tree_node_id|). When this method returns true, the
  // corresponding resource load will be halted until |resume| is invoked. This
  // provides an opportunity for UI thread initializations.
  static bool OverrideBodyForInterceptedResponse(
      int32_t navigating_frame_tree_node_id,
      const GURL& resource_url,
      const std::string& mime_type,
      const std::string& stream_id,
      std::string* payload,
      uint32_t* data_pipe_size,
      base::OnceClosure resume_load = base::DoNothing());

  ~MimeHandlerViewAttachHelper() override;

  // content::RenderProcessHostObserver overrides.
  void RenderProcessHostDestroyed(content::RenderProcessHost* host) override;

  // Starts the attaching process for the |guest_view|'s WebContents to its
  // outer WebContents (embedder WebContents) on the UI thread.
  void AttachToOuterWebContents(MimeHandlerViewGuest* guest_view,
                                int32_t embedder_render_process_id,
                                content::RenderFrameHost* outer_contents_frame,
                                int32_t element_instance_id,
                                bool is_full_page_plugin);

 private:
  // Called after the content layer finishes preparing a frame for attaching to
  // the embedder WebContents. If |plugin_rfh| is nullptr then attaching is not
  // possible and the guest should be destroyed; otherwise it is safe to proceed
  // to attaching the WebContentses.
  void ResumeAttachOrDestroy(int32_t element_instance_id,
                             bool is_full_page_plugin,
                             content::RenderFrameHost* plugin_rfh);

  // Called on UI thread to start observing the frame associated with
  // |frame_tree_node_id| and have the renderer create a
  // MimeHandlerViewFrameContainer as soon as the observed frame is ready, i.e.,
  // the frame has committed the |resource_url| and its child frame (in the same
  // SiteInstance) has been created.
  static void CreateFullPageMimeHandlerView(int32_t frame_tree_node_id,
                                            const GURL& resource_url,
                                            const std::string& mime_type,
                                            const std::string& stream_id,
                                            const std::string& token);

  MimeHandlerViewAttachHelper(content::RenderProcessHost* render_process_host);

  // From the time the MimeHandlerViewGuest starts the attach process
  // (AttachToOuterWebContents) to when the inner WebContents of GuestView
  // attaches to the outer WebContents, there is a gap where the embedder
  // RenderFrameHost (parent frame to the outer contents frame) can go away.
  // Therefore, we keep a weak pointer to the GuestViews here (see
  // https://crbug.com/959572).
  base::flat_map<int32_t, base::WeakPtr<MimeHandlerViewGuest>> pending_guests_;

  content::RenderProcessHost* const render_process_host_;

  base::WeakPtrFactory<MimeHandlerViewAttachHelper> weak_factory_{this};

  DISALLOW_COPY_AND_ASSIGN(MimeHandlerViewAttachHelper);
};

}  // namespace extensions

#endif  // EXTENSIONS_BROWSER_GUEST_VIEW_MIME_HANDLER_VIEW_MIME_HANDLER_VIEW_ATTACH_HELPER_H_