scheduler: Detect load RAIL mode

third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.h

Index: third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.h
diff --git a/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.h b/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.h
index 8ed9ef5107adadf6326f3be80f67021692e64fe7..a679a73cd7f15cd243189631d551a113a9f7f045 100644
--- a/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.h
+++ b/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.h
@@ -63,7 +63,7 @@ class BLINK_PLATFORM_EXPORT RendererSchedulerImpl
     // listeners to find out the actual gesture type. To minimize touch latency,
     // only input handling work should run in this state.
     TOUCHSTART,
-    // The page is loading.
+    // A page is loading.
     LOADING,
     // A continuous gesture (e.g., scroll) which is being handled by the main
     // thread.
@@ -178,6 +178,8 @@ class BLINK_PLATFORM_EXPORT RendererSchedulerImpl
     return task_queue_throttler_.get();
   }
 
+  void OnFirstMeaningfulPaint();
+
  private:
   friend class RendererSchedulerImplTest;
   friend class RendererSchedulerImplForTest;
@@ -264,10 +266,6 @@ class BLINK_PLATFORM_EXPORT RendererSchedulerImpl
   // renderer has been hidden, before going to sleep for good.
   static const int kEndIdleWhenHiddenDelayMillis = 10000;
 
-  // The amount of time for which loading tasks will be prioritized over
-  // other tasks during the initial page load.
-  static const int kRailsInitialLoadingPrioritizationMillis = 1000;
-
   // The amount of time in milliseconds we have to respond to user input as
   // defined by RAILS.
   static const int kRailsResponseTimeMillis = 50;
@@ -414,7 +412,6 @@ class BLINK_PLATFORM_EXPORT RendererSchedulerImpl
     ~AnyThread();
 
     base::TimeTicks last_idle_period_end_time;
-    base::TimeTicks rails_loading_priority_deadline;
     base::TimeTicks fling_compositor_escalation_deadline;
     UserModel user_model;
     bool awaiting_touch_start_response;
@@ -423,6 +420,7 @@ class BLINK_PLATFORM_EXPORT RendererSchedulerImpl
     bool last_gesture_was_compositor_driven;
     bool default_gesture_prevented;
     bool have_seen_touchstart;
+    bool waiting_for_meaningful_paint;
   };
 
   struct CompositorThreadOnly {