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.
5 #ifndef CONTENT_BROWSER_FRAME_HOST_RENDER_FRAME_PROXY_HOST_H_
6 #define CONTENT_BROWSER_FRAME_HOST_RENDER_FRAME_PROXY_HOST_H_
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"
12 class RenderProcessHost;
13 class RenderFrameHostImpl;
14 class RenderViewHostImpl;
18 // When a page's frames are rendered by multiple processes, each renderer has a
19 // full copy of the frame tree. It has full RenderFrames for the frames it is
20 // responsible for rendering and placeholder objects (i.e., RenderFrameProxies)
21 // for frames rendered by other processes.
23 // This class is the browser-side host object for the placeholder. Each node in
24 // the frame tree has a RenderFrameHost for the active SiteInstance and a set
25 // of RenderFrameProxyHost objects - one for all other SiteInstances with
26 // references to this frame. The proxies allow us to keep existing window
27 // references valid over cross-process navigations and route cross-site
28 // asynchronous JavaScript calls, such as postMessage.
30 // For now, RenderFrameProxyHost is created when a RenderFrameHost is swapped
31 // out and acts just as a wrapper. If a RenderFrameHost can be deleted, no
32 // proxy object is created. It is destroyed when the RenderFrameHost is swapped
33 // back in or is no longer referenced and is therefore deleted.
35 // Long term, RenderFrameProxyHost will be created whenever a cross-site
36 // navigation occurs and a reference to the frame navigating needs to be kept
37 // alive. A RenderFrameProxyHost and a RenderFrameHost for the same SiteInstance
38 // can exist at the same time, but only one will be "active" at a time.
39 // There are two cases where the two objects will coexist:
40 // * When navigating cross-process and there is already a RenderFrameProxyHost
41 // for the new SiteInstance. A pending RenderFrameHost is created, but it is
42 // not used until it commits. At that point, RenderFrameHostManager transitions
43 // the pending RenderFrameHost to the active one and deletes the proxy.
44 // * When navigating cross-process and the existing document has an unload
45 // event handler. When the new navigation commits, RenderFrameHostManager
46 // creates a RenderFrameProxyHost for the old SiteInstance and uses it going
47 // forward. It also instructs the RenderFrameHost to run the unload event
48 // handler and is kept alive for the duration. Once the event handling is
49 // complete, the RenderFrameHost is deleted.
50 class RenderFrameProxyHost {
52 explicit RenderFrameProxyHost(
53 scoped_ptr<RenderFrameHostImpl> render_frame_host);
54 ~RenderFrameProxyHost();
56 RenderProcessHost* GetProcess() {
57 return render_frame_host_->GetProcess();
60 SiteInstance* GetSiteInstance() {
61 return site_instance_.get();
64 // TODO(nasko): The following methods should be removed when swapping out
65 // of RenderFrameHosts is no longer used.
66 RenderFrameHostImpl* render_frame_host() {
67 return render_frame_host_.get();
69 RenderViewHostImpl* render_view_host() {
70 return render_frame_host_->render_view_host();
72 scoped_ptr<RenderFrameHostImpl> PassFrameHost() {
73 return render_frame_host_.Pass();
77 scoped_refptr<SiteInstance> site_instance_;
79 // TODO(nasko): For now, hide the RenderFrameHost inside the proxy, but remove
80 // it once we have all the code support for proper proxy objects.
81 scoped_ptr<RenderFrameHostImpl> render_frame_host_;
83 DISALLOW_COPY_AND_ASSIGN(RenderFrameProxyHost);
88 #endif // CONTENT_BROWSER_FRAME_HOST_RENDER_FRAME_PROXY_HOST_H_