Provision to start base::SimpleTestTickClock at initial ticks

base/test/simple_test_tick_clock.h

Index: base/test/simple_test_tick_clock.h
diff --git a/base/test/simple_test_tick_clock.h b/base/test/simple_test_tick_clock.h
index aebdebcbcf54e7016a1629b5405eb40cbf22d801..8efe241bba4cae09614a1511b4ecbf9810e225d3 100644
--- a/base/test/simple_test_tick_clock.h
+++ b/base/test/simple_test_tick_clock.h
@@ -17,8 +17,9 @@ namespace base {
 // called from any thread.
 class SimpleTestTickClock : public TickClock {
  public:
-  // Starts off with a clock set to TimeTicks().
-  SimpleTestTickClock();
+  // Start off with a clock set to some initial tick(s)
+  // Avoids having to Advance(initial) for tests
+  SimpleTestTickClock(TimeTicks initial);
   ~SimpleTestTickClock() override;
 
   TimeTicks NowTicks() override;