Assert event timestamp to be monotonic and not from future

content/shell/renderer/layout_test/blink_test_runner.h

Index: content/shell/renderer/layout_test/blink_test_runner.h
diff --git a/content/shell/renderer/layout_test/blink_test_runner.h b/content/shell/renderer/layout_test/blink_test_runner.h
index 5756f6bb85d36cfd327cc626d4a694ec22741281..7ee31ccc0b9fb0d7d129f866e8ca7128388c1508 100644
--- a/content/shell/renderer/layout_test/blink_test_runner.h
+++ b/content/shell/renderer/layout_test/blink_test_runner.h
@@ -155,6 +155,9 @@ class BlinkTestRunner : public RenderViewObserver,
   float GetDeviceScaleFactor() const override;
   void RunIdleTasks(const base::Closure& callback) override;
 
+  void SetMockMonotonicTimeFunction(
+      const base::Callback<double()>& time_function) const override;
+
   // Resets a RenderView to a known state for layout tests. It is used both when
   // a RenderView is created and when reusing an existing RenderView for the
   // next test case.
@@ -214,6 +217,12 @@ class BlinkTestRunner : public RenderViewObserver,
 
   std::unique_ptr<LeakDetector> leak_detector_;
 
+  static base::Callback<double()> time_function_;
+  static double returnMockTime() {
+    DCHECK(!time_function_.is_null());
+    return time_function_.Run();
+  }
+
   DISALLOW_COPY_AND_ASSIGN(BlinkTestRunner);
 };