Report user actions when gesture starts and stops in user_model.

components/scheduler/renderer/user_model.h

Index: components/scheduler/renderer/user_model.h
diff --git a/components/scheduler/renderer/user_model.h b/components/scheduler/renderer/user_model.h
index f93b10beadcfa0f2cfbffed5454f3d3e62b2ba35..8028ba4a73597f538e45e96f06eae7323ee5a6d1 100644
--- a/components/scheduler/renderer/user_model.h
+++ b/components/scheduler/renderer/user_model.h
@@ -5,6 +5,7 @@
 #ifndef COMPONENTS_SCHEDULER_RENDERER_USER_MODEL_H_
 #define COMPONENTS_SCHEDULER_RENDERER_USER_MODEL_H_
 
+#include "base/feature_list.h"
 #include "base/macros.h"
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
@@ -12,11 +13,20 @@
 #include "components/scheduler/scheduler_export.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
 
+namespace base {
+class SingleThreadTaskRunner;
+}  // namespace base
+
 namespace scheduler {
 
+namespace features {
+SCHEDULER_EXPORT extern const base::Feature kRecordSchedulerGestureActions;
+}  // namespace features
+
 class SCHEDULER_EXPORT UserModel {
  public:
-  UserModel();
+  explicit UserModel(
+      scoped_refptr<base::SingleThreadTaskRunner> default_task_runner);
   ~UserModel();
 
   // Tells us that the system started processing an input event. Must be paired
@@ -67,6 +77,9 @@ class SCHEDULER_EXPORT UserModel {
       const base::TimeTicks now,
       base::TimeDelta* prediction_valid_duration) const;
 
+  // Task runner used to execute tasks on the main thread.
+  scoped_refptr<base::SingleThreadTaskRunner> default_task_runner_;
+
   int pending_input_event_count_;
   base::TimeTicks last_input_signal_time_;
   base::TimeTicks last_gesture_start_time_;