7 files changed, 11 insertions, 40 deletions
diff --git a/dom/console/Console.cpp b/dom/console/Console.cpp
index 79e3eadc5..1ecf1f7fd 100755
--- a/dom/console/Console.cpp
+++ b/dom/console/Console.cpp
@@ -1337,7 +1337,7 @@ Console::MethodInternal(JSContext* aCx, MethodName aMethodName,
       MOZ_ASSERT(workerPrivate);
 
       TimeDuration duration =
-        mozilla::TimeStamp::Now() - workerPrivate->NowBaseTimeStamp();
+        mozilla::TimeStamp::Now() - workerPrivate->CreationTimeStamp();
 
       monotonicTimer = TimerClamping::ReduceMsTimeValue(duration.ToMilliseconds());
     }
diff --git a/dom/console/Console.h b/dom/console/Console.h
index b334d79f9..2f375c8eb 100644
--- a/dom/console/Console.h
+++ b/dom/console/Console.h
@@ -258,9 +258,8 @@ private:
   // the max number of timers is reached.
   // * aCx - the JSContext rooting aName.
   // * aName - this is (should be) the name of the timer as JS::Value.
-  // * aTimestamp - the monotonicTimer for this context (taken from
-  //                window->performance.now() or from Now() -
-  //                workerPrivate->NowBaseTimeStamp() in workers.
+  // * aTimestamp - the monotonicTimer for this context taken from
+  //                performance.now().
   // * aTimerLabel - This label will be populated with the aName converted to a
   //                 string.
   // * aTimerValue - the StartTimer value stored into (or taken from)
@@ -290,9 +289,8 @@ private:
   // the aName timer doesn't exist in the mTimerRegistry.
   // * aCx - the JSContext rooting aName.
   // * aName - this is (should be) the name of the timer as JS::Value.
-  // * aTimestamp - the monotonicTimer for this context (taken from
-  //                window->performance.now() or from Now() -
-  //                workerPrivate->NowBaseTimeStamp() in workers.
+  // * aTimestamp - the monotonicTimer for this context taken from
+  //                performance.now().
   // * aTimerLabel - This label will be populated with the aName converted to a
   //                 string.
   // * aTimerDuration - the difference between aTimestamp and when the timer
diff --git a/dom/events/Event.cpp b/dom/events/Event.cpp
index 7e19cd74d..4e39675da 100755
--- a/dom/events/Event.cpp
+++ b/dom/events/Event.cpp
@@ -1146,15 +1146,14 @@ Event::TimeStampImpl() const
     return perf->GetDOMTiming()->TimeStampToDOMHighRes(mEvent->mTimeStamp);
   }
 
-  // For dedicated workers, we should make times relative to the navigation
-  // start of the document that created the worker, which is the same as the
-  // timebase for performance.now().
+  // For dedicated workers, we should make times relative to the creation time
+  // of the worker, which is the same as the timebase for performance.now().
   workers::WorkerPrivate* workerPrivate =
     workers::GetCurrentThreadWorkerPrivate();
   MOZ_ASSERT(workerPrivate);
 
   TimeDuration duration =
-    mEvent->mTimeStamp - workerPrivate->NowBaseTimeStamp();
+    mEvent->mTimeStamp - workerPrivate->CreationTimeStamp();
   return duration.ToMilliseconds();
 }
 
diff --git a/dom/performance/PerformanceMainThread.cpp b/dom/performance/PerformanceMainThread.cpp
index 5eac15afd..5c259cfb8 100644
--- a/dom/performance/PerformanceMainThread.cpp
+++ b/dom/performance/PerformanceMainThread.cpp
@@ -75,7 +75,7 @@ PerformanceTiming*
 PerformanceMainThread::Timing()
 {
   if (!mTiming) {
-    // For navigation timing, the third argument (an nsIHtttpChannel) is null
+    // For navigation timing, the third argument (an nsIHttpChannel) is null
     // since the cross-domain redirect were already checked.  The last argument
     // (zero time) for performance.timing is the navigation start value.
     mTiming = new PerformanceTiming(this, mChannel, nullptr,
diff --git a/dom/performance/PerformanceWorker.cpp b/dom/performance/PerformanceWorker.cpp
index 17820d434..f10c58446 100644
--- a/dom/performance/PerformanceWorker.cpp
+++ b/dom/performance/PerformanceWorker.cpp
@@ -41,13 +41,13 @@ PerformanceWorker::InsertUserEntry(PerformanceEntry* aEntry)
 TimeStamp
 PerformanceWorker::CreationTimeStamp() const
 {
-  return mWorkerPrivate->NowBaseTimeStamp();
+  return mWorkerPrivate->CreationTimeStamp();
 }
 
 DOMHighResTimeStamp
 PerformanceWorker::CreationTime() const
 {
-  return mWorkerPrivate->NowBaseTime();
+  return mWorkerPrivate->CreationTime();
 }
 
 } // dom namespace
diff --git a/dom/workers/WorkerPrivate.cpp b/dom/workers/WorkerPrivate.cpp
index bd8a33032..8848e881a 100644
--- a/dom/workers/WorkerPrivate.cpp
+++ b/dom/workers/WorkerPrivate.cpp
@@ -2419,8 +2419,6 @@ WorkerPrivateParent<Derived>::WorkerPrivateParent(
     MOZ_ASSERT_IF(mIsChromeWorker, mIsSecureContext);
 
     MOZ_ASSERT(IsDedicatedWorker());
-    mNowBaseTimeStamp = aParent->NowBaseTimeStamp();
-    mNowBaseTimeHighRes = aParent->NowBaseTime();
 
     if (aParent->mParentFrozen) {
       Freeze(nullptr);
@@ -2451,18 +2449,6 @@ WorkerPrivateParent<Derived>::WorkerPrivateParent(
                  .creationOptions().setSecureContext(true);
     }
 
-    if (IsDedicatedWorker() && mLoadInfo.mWindow &&
-        mLoadInfo.mWindow->GetPerformance()) {
-      mNowBaseTimeStamp = mLoadInfo.mWindow->GetPerformance()->GetDOMTiming()->
-        GetNavigationStartTimeStamp();
-      mNowBaseTimeHighRes =
-      mLoadInfo.mWindow->GetPerformance()->GetDOMTiming()->
-        GetNavigationStartHighRes();
-    } else {
-      mNowBaseTimeStamp = CreationTimeStamp();
-      mNowBaseTimeHighRes = CreationTime();
-    }
-
     // Our parent can get suspended after it initiates the async creation
     // of a new worker thread.  In this case suspend the new worker as well.
     if (mLoadInfo.mWindow && mLoadInfo.mWindow->IsSuspended()) {
diff --git a/dom/workers/WorkerPrivate.h b/dom/workers/WorkerPrivate.h
index 465c0f9a3..e15beb955 100644
--- a/dom/workers/WorkerPrivate.h
+++ b/dom/workers/WorkerPrivate.h
@@ -216,8 +216,6 @@ private:
   WorkerType mWorkerType;
   TimeStamp mCreationTimeStamp;
   DOMHighResTimeStamp mCreationTimeHighRes;
-  TimeStamp mNowBaseTimeStamp;
-  DOMHighResTimeStamp mNowBaseTimeHighRes;
 
 protected:
   // The worker is owned by its thread, which is represented here.  This is set
@@ -579,16 +577,6 @@ public:
     return mCreationTimeHighRes;
   }
 
-  TimeStamp NowBaseTimeStamp() const
-  {
-    return mNowBaseTimeStamp;
-  }
-
-  DOMHighResTimeStamp NowBaseTime() const
-  {
-    return mNowBaseTimeHighRes;
-  }
-
   nsIPrincipal*
   GetPrincipal() const
   {