Expose the timestamp associated with a user gesture, and make it possible to recreate a new user ge…

Source/platform/UserGestureIndicator.h

Index: Source/platform/UserGestureIndicator.h
diff --git a/Source/platform/UserGestureIndicator.h b/Source/platform/UserGestureIndicator.h
index 50831e0b00a661c952fa91a4bab8912d2e50fb3d..398f2b516a4aeeb301aedce3aa6c0ec5fbd3af2f 100644
--- a/Source/platform/UserGestureIndicator.h
+++ b/Source/platform/UserGestureIndicator.h
@@ -48,6 +48,7 @@ public:
     virtual bool hasGestures() const = 0;
     virtual void setOutOfProcess() = 0;
     virtual void setJavascriptPrompt() = 0;
+    virtual double timestamp() const = 0;
 };
 
 class PLATFORM_EXPORT UserGestureIndicatorDisabler {
@@ -73,6 +74,7 @@ public:
 
     explicit UserGestureIndicator(ProcessingUserGestureState);
     explicit UserGestureIndicator(PassRefPtr<UserGestureToken>);
+    explicit UserGestureIndicator(double timestamp);
     ~UserGestureIndicator();