Validate that ui::Event::time_stamp comes from the same clock as TimeTicks::Now

content/browser/renderer_host/render_widget_host_view_mac_unittest.mm

Index: content/browser/renderer_host/render_widget_host_view_mac_unittest.mm
diff --git a/content/browser/renderer_host/render_widget_host_view_mac_unittest.mm b/content/browser/renderer_host/render_widget_host_view_mac_unittest.mm
index 5fd59a1b9c128046edafc2bbd32a978955458435..efa4daa5b0b31ad2f646723532fee655032d8cfd 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac_unittest.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac_unittest.mm
@@ -16,6 +16,7 @@
 #include "base/run_loop.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/test/histogram_tester.h"
+#include "base/test/simple_test_tick_clock.h"
 #include "content/browser/browser_thread_impl.h"
 #include "content/browser/compositor/test/no_transport_image_transport_factory.h"
 #include "content/browser/frame_host/render_widget_host_view_guest.h"
@@ -36,6 +37,7 @@
 #include "testing/gtest_mac.h"
 #import "third_party/ocmock/OCMock/OCMock.h"
 #import "third_party/ocmock/ocmock_extensions.h"
+#include "ui/events/base_event_utils.h"
 #include "ui/events/latency_info.h"
 #include "ui/events/test/cocoa_test_event_utils.h"
 #import "ui/gfx/test/ui_cocoa_test_helper.h"
@@ -225,6 +227,8 @@ gfx::Rect GetExpectedRect(const gfx::Point& origin,
 NSEvent* MockScrollWheelEventWithPhase(SEL mockPhaseSelector, int32_t delta) {
   CGEventRef cg_event =
       CGEventCreateScrollWheelEvent(NULL, kCGScrollEventUnitLine, 1, delta, 0);
+  CGEventTimestamp timestamp = 0;
+  CGEventSetTimestamp(cg_event, timestamp);
   NSEvent* event = [NSEvent eventWithCGEvent:cg_event];
   CFRelease(cg_event);
   method_setImplementation(
@@ -237,7 +241,12 @@ NSEvent* MockScrollWheelEventWithPhase(SEL mockPhaseSelector, int32_t delta) {
 
 class RenderWidgetHostViewMacTest : public RenderViewHostImplTestHarness {
  public:
-  RenderWidgetHostViewMacTest() : old_rwhv_(NULL), rwhv_mac_(NULL) {}
+  RenderWidgetHostViewMacTest() : old_rwhv_(NULL), rwhv_mac_(NULL) {
+    std::unique_ptr<base::SimpleTestTickClock> mock_clock(
+        new base::SimpleTestTickClock());
+    mock_clock->Advance(base::TimeDelta::FromMilliseconds(100));
+    ui::SetEventTickClockForTesting(std::move(mock_clock));
+  }
 
   void SetUp() override {
     RenderViewHostImplTestHarness::SetUp();