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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CONTENT_BROWSER_FRAME_HOST_RENDER_FRAME_PROXY_HOST_H_
      6 #define CONTENT_BROWSER_FRAME_HOST_RENDER_FRAME_PROXY_HOST_H_
      7 
      8 #include "base/memory/scoped_ptr.h"
      9 #include "content/browser/frame_host/render_frame_host_impl.h"
     10 #include "content/browser/site_instance_impl.h"
     11 #include "ipc/ipc_listener.h"
     12 #include "ipc/ipc_sender.h"
     13 
     14 namespace content {
     15 
     16 class CrossProcessFrameConnector;
     17 class FrameTreeNode;
     18 class RenderProcessHost;
     19 class RenderFrameHostImpl;
     20 class RenderViewHostImpl;
     21 class RenderWidgetHostView;
     22 
     23 // When a page's frames are rendered by multiple processes, each renderer has a
     24 // full copy of the frame tree. It has full RenderFrames for the frames it is
     25 // responsible for rendering and placeholder objects (i.e., RenderFrameProxies)
     26 // for frames rendered by other processes.
     27 //
     28 // This class is the browser-side host object for the placeholder. Each node in
     29 // the frame tree has a RenderFrameHost for the active SiteInstance and a set
     30 // of RenderFrameProxyHost objects - one for all other SiteInstances with
     31 // references to this frame. The proxies allow us to keep existing window
     32 // references valid over cross-process navigations and route cross-site
     33 // asynchronous JavaScript calls, such as postMessage.
     34 //
     35 // For now, RenderFrameProxyHost is created when a RenderFrameHost is swapped
     36 // out and acts just as a wrapper. It is destroyed when the RenderFrameHost is
     37 // swapped back in or is no longer referenced and is therefore deleted.
     38 //
     39 // Long term, RenderFrameProxyHost will be created whenever a cross-site
     40 // navigation occurs and a reference to the frame navigating needs to be kept
     41 // alive. A RenderFrameProxyHost and a RenderFrameHost for the same SiteInstance
     42 // can exist at the same time, but only one will be "active" at a time.
     43 // There are two cases where the two objects will coexist:
     44 // * When navigating cross-process and there is already a RenderFrameProxyHost
     45 // for the new SiteInstance. A pending RenderFrameHost is created, but it is
     46 // not used until it commits. At that point, RenderFrameHostManager transitions
     47 // the pending RenderFrameHost to the active one and deletes the proxy.
     48 // * When navigating cross-process and the existing document has an unload
     49 // event handler. When the new navigation commits, RenderFrameHostManager
     50 // creates a RenderFrameProxyHost for the old SiteInstance and uses it going
     51 // forward. It also instructs the RenderFrameHost to run the unload event
     52 // handler and is kept alive for the duration. Once the event handling is
     53 // complete, the RenderFrameHost is deleted.
     54 class RenderFrameProxyHost
     55     : public IPC::Listener,
     56       public IPC::Sender {
     57  public:
     58   RenderFrameProxyHost(SiteInstance* site_instance,
     59                        FrameTreeNode* frame_tree_node);
     60   virtual ~RenderFrameProxyHost();
     61 
     62   RenderProcessHost* GetProcess() {
     63     return site_instance_->GetProcess();
     64   }
     65 
     66   int GetRoutingID() {
     67     return routing_id_;
     68   }
     69 
     70   SiteInstance* GetSiteInstance() {
     71     return site_instance_.get();
     72   }
     73 
     74   void SetChildRWHView(RenderWidgetHostView* view);
     75 
     76   // TODO(nasko): The following methods should be removed once we don't have a
     77   // swapped out state on RenderFrameHosts. See https://crbug.com/357747.
     78   RenderFrameHostImpl* render_frame_host() {
     79     return render_frame_host_.get();
     80   }
     81   RenderViewHostImpl* GetRenderViewHost();
     82 
     83   void TakeFrameHostOwnership(
     84       scoped_ptr<RenderFrameHostImpl> render_frame_host) {
     85     render_frame_host_ = render_frame_host.Pass();
     86   }
     87   scoped_ptr<RenderFrameHostImpl> PassFrameHostOwnership();
     88 
     89   // IPC::Sender
     90   virtual bool Send(IPC::Message* msg) OVERRIDE;
     91 
     92   // IPC::Listener
     93   virtual bool OnMessageReceived(const IPC::Message& msg) OVERRIDE;
     94 
     95   CrossProcessFrameConnector* cross_process_frame_connector() {
     96     return cross_process_frame_connector_.get();
     97   }
     98 
     99  private:
    100   // This RenderFrameProxyHost's routing id.
    101   int routing_id_;
    102 
    103   // The SiteInstance this proxy is associated with.
    104   scoped_refptr<SiteInstance> site_instance_;
    105 
    106   // The node in the frame tree where this proxy is located.
    107   FrameTreeNode* frame_tree_node_;
    108 
    109   // When a RenderFrameHost is in a different process from its parent in the
    110   // frame tree, this class connects its associated RenderWidgetHostView
    111   // to this RenderFrameProxyHost, which corresponds to the same frame in the
    112   // parent's renderer process.
    113   scoped_ptr<CrossProcessFrameConnector> cross_process_frame_connector_;
    114 
    115   // TODO(nasko): This can be removed once we don't have a swapped out state on
    116   // RenderFrameHosts. See https://crbug.com/357747.
    117   scoped_ptr<RenderFrameHostImpl> render_frame_host_;
    118 
    119   DISALLOW_COPY_AND_ASSIGN(RenderFrameProxyHost);
    120 };
    121 
    122 }  // namespace
    123 
    124 #endif  // CONTENT_BROWSER_FRAME_HOST_RENDER_FRAME_PROXY_HOST_H_
    125