Add a signal to the scheduler that a navigation is expected

components/scheduler/renderer/renderer_scheduler.h

Index: components/scheduler/renderer/renderer_scheduler.h
diff --git a/components/scheduler/renderer/renderer_scheduler.h b/components/scheduler/renderer/renderer_scheduler.h
index d605e52ce620fc7aa0f120249dd1c72a0379dd5d..3ec03e0b23a94a009bdbc1de057ad5cc80633b2b 100644
--- a/components/scheduler/renderer/renderer_scheduler.h
+++ b/components/scheduler/renderer/renderer_scheduler.h
@@ -106,10 +106,20 @@ class SCHEDULER_EXPORT RendererScheduler : public ChildScheduler {
   // Must be called on the main thread.
   virtual void OnRendererForegrounded() = 0;
 
-  // Tells the scheduler that a page load has started.  The scheduler will
+  // Tells the scheduler that a navigation is expected. The scheduler will
+  // ensure that loading tasks are not blocked even if they are expensive.
+  // This mode lasts until either OnNavigationStarted or OnNavigationCanceled is
+  // called.
+  virtual void OnNavigationExpected() = 0;
+
+  // Tells the scheduler that an expected navigation was canceled. The
+  // scheduler may now block expensive tasks.
+  virtual void OnNavigationCanceled() = 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 OnPageLoadStarted() = 0;
+  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