Use high precision timestamp for Event.timestamp

third_party/WebKit/Source/core/timing/PerformanceBase.h

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2012 Intel Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 15 matching lines @@
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef PerformanceBase_h
 #define PerformanceBase_h
 
 #include "core/CoreExport.h"
+#include "core/dom/DOMHighResTimeStamp.h"
 #include "core/events/EventTarget.h"
 #include "core/timing/PerformanceEntry.h"
 #include "platform/Timer.h"
 #include "platform/heap/Handle.h"
 #include "wtf/RefCounted.h"
 #include "wtf/RefPtr.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 class Document;
 class ExceptionState;
 class PerformanceObserver;
 class PerformanceTiming;
 class ResourceTimingInfo;
 class UserTiming;
 
 using PerformanceEntryVector = HeapVector<Member<PerformanceEntry>>;
 using PerformanceObservers = HeapListHashSet<Member<PerformanceObserver>>;
 
 class CORE_EXPORT PerformanceBase : public RefCountedGarbageCollectedEventTargetWithInlineData<PerformanceBase> {
     REFCOUNTED_GARBAGE_COLLECTED_EVENT_TARGET(PerformanceBase);
 public:
     ~PerformanceBase() override;
 
     const AtomicString& interfaceName() const override;
 
     virtual PerformanceTiming* timing() const;
-    double now() const;
+
+    // Reduce the resolution to 5µs to prevent timing attacks. See:
+    // http://www.w3.org/TR/hr-time-2/#privacy-security
+    static double clampTimeResolution(double timeSeconds);
+
+    // Translate given platform monotonic time in seconds into a high resolution
+    // DOMHighResTimeStamp in milliseconds. The result timestamp is relative to
+    // document's time origin and has a time resolution that is safe for
+    // exposing to web.
+    DOMHighResTimeStamp monotonicTimeToDOMHighResTimeStamp(double) const;
+    DOMHighResTimeStamp now() const;
 
     double timeOrigin() const { return m_timeOrigin; }
 
-    static double clampTimeResolution(double timeSeconds);
-
     PerformanceEntryVector getEntries() const;
     PerformanceEntryVector getEntriesByType(const String& entryType);
     PerformanceEntryVector getEntriesByName(const String& name, const String& entryType);
 
     void clearResourceTimings();
     void setResourceTimingBufferSize(unsigned);
 
     DEFINE_ATTRIBUTE_EVENT_LISTENER(resourcetimingbufferfull);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(webkitresourcetimingbufferfull);
 
@@ skipping 47 matching lines @@
     PerformanceEntryTypeMask m_observerFilterOptions;
     PerformanceObservers m_observers;
     PerformanceObservers m_activeObservers;
     PerformanceObservers m_suspendedObservers;
     Timer<PerformanceBase> m_deliverObservationsTimer;
 };
 
 } // namespace blink
 
 #endif // PerformanceBase_h