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

content/browser/transition_request_manager.h

Index: content/browser/transition_request_manager.h
diff --git a/content/browser/transition_request_manager.h b/content/browser/transition_request_manager.h
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+// Copyright 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"
+
+template <typename T>
+struct DefaultSingletonTraits;
+
+namespace content {
+
+// TransitionRequestManager is used to handle bookkeeping for transition
+// requests and responses.
+//
+// TransitionRequestManager is a singleton and should only be accessed on the IO
+// thread.
+//
+class TransitionRequestManager {
+ public:
+  // Returns the singleton instance.
+  static TransitionRequestManager* GetInstance();
+
+  // Returns whether the RenderFrameHost 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 process_id, int render_frame_id);
+
+  // Sets whether the RenderFrameHost specified by the given IDs currently has a
+  // pending transition request.
+  void SetHasPendingTransitionRequest(int process_id,
+                                      int render_frame_id,
+                                      bool has_pending);
+
+ private:
+  friend struct DefaultSingletonTraits<TransitionRequestManager>;
+  typedef std::set<std::pair<int, int> > RenderFrameSet;
+
+  TransitionRequestManager();
+  ~TransitionRequestManager();
+
+  // Set of (render_process_host_id, render_frame_id) pairs of all
+  // RenderFrameHosts that have pending transition requests. Used to pass
+  // information to the CrossSiteResourceHandler without doing a round-trip
+  // between IO->UI->IO threads.
+  RenderFrameSet pending_transition_frames_;
+
+  DISALLOW_COPY_AND_ASSIGN(TransitionRequestManager);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_TRANSITION_REQUEST_MANAGER_H_