Navigation transitions: Block first response until after transitions have run.

content/browser/transition_request_manager.h

+// Copyright (c) 2014 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 CONTENT_BROWSER_TRANSITION_REQUEST_MANAGER_H_
+#define CONTENT_BROWSER_TRANSITION_REQUEST_MANAGER_H_
+
+#include <set>
+#include <utility>
+
+#include "base/basictypes.h"
+#include "base/synchronization/lock.h"
+
+template <typename T> struct DefaultSingletonTraits;
+
+namespace content {
+
+// TransitionRequestManager is used to handle bookkeeping for transition
+// requests and responses between the UI and IO threads.
+//
+// TransitionRequestManager is a singleton that may be used on any thread.
+//
+class TransitionRequestManager {
+ public:
+  // Returns the singleton instance.
+  static TransitionRequestManager* GetInstance();
+
+  // Returns whether the RenderViewHost specified by the given IDs currently
+  // has a pending transition request. If so, we will have to delay the
+  // response until the embedder resumes the request.
+  bool HasPendingTransitionRequest(int renderer_id, int render_view_id);

[nasko, 2014/05/28 22:59:00]

What is renderer_id? Is it the process id or something else? It should be named
in a self-describing way.

[shatch, 2014/05/29 21:41:22]

Done.

+
+  // Sets whether the RenderViewHost specified by the given IDs currently has a

[nasko, 2014/05/28 22:59:00]

Navigations happen through RenderFrameHost these days, so we should stay away
from using RenderViewHosts here.

[shatch, 2014/05/29 21:41:22]

Changed the comment to reflect being called by the RFH instead. I was just using
the RVH's id since I could get at that from both the CSRH and from the
RenderFrameHostManager, which seems to be the way the CrossSiteRequestManager
tracks requests too. Is there something else I could use here instead?

[nasko, 2014/06/02 21:59:33]

I can see this called only from
RenderFrameHostImpl::SetHasPendingTransitionRequest. Where do we need the
RenderFrameHost routing ID that we can't get it?

[shatch, 2014/06/02 23:40:40]

Moved everything to RFH per offline discussion.

+  // pending transition request. Called by RenderViewHost on the UI thread.
+  void SetHasPendingTransitionRequest(int renderer_id,
+                                      int render_view_id,
+                                      bool has_pending);
+
+ private:
+  friend struct DefaultSingletonTraits<TransitionRequestManager>;
+  typedef std::set<std::pair<int, int> > RenderViewSet;
+
+  TransitionRequestManager();
+  ~TransitionRequestManager();
+
+  // You must acquire this lock before reading or writing any members of this
+  // class.  You must not block while holding this lock.
+  base::Lock lock_;
+
+  // Set of (render_process_host_id, render_view_id) pairs of all
+  // RenderViewHosts that have pending transition requests. Used to pass
+  // information to the CrossSiteResourceHandler without doing a round-trip
+  // between IO->UI->IO threads.
+  RenderViewSet pending_transition_views_;
+
+  DISALLOW_COPY_AND_ASSIGN(TransitionRequestManager);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_TRANSITION_REQUEST_MANAGER_H_