Allow expensive task blocking if there is pending iframe navigation

components/scheduler/renderer/renderer_scheduler.h

 // 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 COMPONENTS_SCHEDULER_RENDERER_RENDERER_SCHEDULER_H_
 #define COMPONENTS_SCHEDULER_RENDERER_RENDERER_SCHEDULER_H_
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 110 matching lines @@
   // driven by this process. A stricter condition than |OnRendererHidden()|, the
   // process is assumed to be foregrounded when the scheduler is constructed.
   // Must be called on the main thread.
   virtual void OnRendererBackgrounded() = 0;
 
   // Tells the scheduler that the renderer process has been foregrounded.
   // This is the assumed state when the scheduler is constructed.
   // Must be called on the main thread.
   virtual void OnRendererForegrounded() = 0;
 
-  // Tells the scheduler that a navigation task is pending. While any navigation
-  // tasks are pending, the scheduler will ensure that loading tasks are not
-  // blocked even if they are expensive. Must be called on the main thread.
-  virtual void AddPendingNavigation() = 0;
+  // Tells the scheduler that a navigation task is pending. While any main-frame
+  // navigation tasks are pending, the scheduler will ensure that loading tasks
+  // are not blocked even if they are expensive. Must be called on the main
+  // thread.
+  virtual void AddPendingNavigation(bool main_frame_navigating) = 0;
 
   // Tells the scheduler that a navigation task is no longer pending.
   // Must be called on the main thread.
-  virtual void RemovePendingNavigation() = 0;
+  virtual void RemovePendingNavigation(bool main_frame_navigating) = 0;
 
   // Tells the scheduler that a navigation has started.  The scheduler will
   // prioritize loading tasks for a short duration afterwards.
   // Must be called from the main thread.
   virtual void OnNavigationStarted() = 0;
 
   // Returns true if the scheduler has reason to believe that high priority work
   // may soon arrive on the main thread, e.g., if gesture events were observed
   // recently.
   // Must be called from the main thread.
@@ skipping 17 matching lines @@
       base::trace_event::BlameContext* blame_context) = 0;
 
  protected:
   RendererScheduler();
   DISALLOW_COPY_AND_ASSIGN(RendererScheduler);
 };
 
 }  // namespace scheduler
 
 #endif  // COMPONENTS_SCHEDULER_RENDERER_RENDERER_SCHEDULER_H_