Bug 1772417 - correct web-platform convert name to timestamp. r=sefeng

This fixes the performance-measure-invalid.worker.html test. The test failed
because User Timing L3 section 4.2, "Convert a name to a timestamp", was not
implemented - the code was presumably residual from an earlier version of User
Timing. In particular, we never threw if the global object was not a Window. We
also corrected the code order for section 4.1, "Convert a mark to a timestamp",
which was incorrect but didn't cause any tests to fail.

Differential Revision: https://phabricator.services.mozilla.com/D154820

dom/performance/Performance.cpp

@@ -431,6 +431,10 @@ bool Performance::IsPerformanceTimingAttribute(const nsAString& aName) const {
 
 DOMHighResTimeStamp Performance::ConvertMarkToTimestampWithString(
     const nsAString& aName, ErrorResult& aRv) {
+  if (IsPerformanceTimingAttribute(aName)) {
+    return ConvertNameToTimestamp(aName, aRv);
+  }
+
   AutoTArray<RefPtr<PerformanceEntry>, 1> arr;
   Optional<nsAString> typeParam;
   nsAutoString str;
@@ -441,20 +445,10 @@ DOMHighResTimeStamp Performance::ConvertMarkToTimestampWithString(
     return arr.LastElement()->StartTime();
   }
 
-  if (!IsPerformanceTimingAttribute(aName)) {
-    nsPrintfCString errorMsg("Given mark name, %s, is unknown",
-                             NS_ConvertUTF16toUTF8(aName).get());
-    aRv.ThrowSyntaxError(errorMsg);
-    return 0;
-  }
-
-  DOMHighResTimeStamp ts = GetPerformanceTimingFromString(aName);
-  if (!ts) {
-    aRv.Throw(NS_ERROR_DOM_INVALID_ACCESS_ERR);
-    return 0;
-  }
-
-  return ts - CreationTime();
+  nsPrintfCString errorMsg("Given mark name, %s, is unknown",
+                           NS_ConvertUTF16toUTF8(aName).get());
+  aRv.ThrowSyntaxError(errorMsg);
+  return 0;
 }
 
 DOMHighResTimeStamp Performance::ConvertMarkToTimestampWithDOMHighResTimeStamp(
@@ -493,6 +487,39 @@ DOMHighResTimeStamp Performance::ConvertMarkToTimestamp(
       aAttribute, aMarkNameOrTimestamp.GetAsDouble(), aRv);
 }
 
+DOMHighResTimeStamp Performance::ConvertNameToTimestamp(const nsAString& aName,
+                                                        ErrorResult& aRv) {
+  if (!IsGlobalObjectWindow()) {
+    nsPrintfCString errorMsg(
+        "Cannot get PerformanceTiming attribute values for non-Window global "
+        "object. Given: %s",
+        NS_ConvertUTF16toUTF8(aName).get());
+    aRv.ThrowTypeError(errorMsg);
+    return 0;
+  }
+
+  if (aName.EqualsASCII("navigationStart")) {
+    return 0;
+  }
+
+  // We use GetPerformanceTimingFromString, rather than calling the
+  // navigationStart method timing function directly, because the former handles
+  // reducing precision against timing attacks.
+  const DOMHighResTimeStamp startTime =
+      GetPerformanceTimingFromString(u"navigationStart"_ns);
+  const DOMHighResTimeStamp endTime = GetPerformanceTimingFromString(aName);
+  MOZ_ASSERT(endTime >= 0);
+  if (endTime == 0) {
+    nsPrintfCString errorMsg(
+        "Given PerformanceTiming attribute, %s, isn't available yet",
+        NS_ConvertUTF16toUTF8(aName).get());
+    aRv.ThrowInvalidAccessError(errorMsg);
+    return 0;
+  }
+
+  return endTime - startTime;
+}
+
 DOMHighResTimeStamp Performance::ResolveEndTimeForMeasure(
     const Optional<nsAString>& aEndMark,
     const Maybe<const PerformanceMeasureOptions&>& aOptions, ErrorResult& aRv) {

dom/performance/Performance.h

@@ -223,6 +223,9 @@ class Performance : public DOMEventTargetHelper {
       const ResolveTimestampAttribute aAttribute,
       const OwningStringOrDouble& aMarkNameOrTimestamp, ErrorResult& aRv);
 
+  DOMHighResTimeStamp ConvertNameToTimestamp(const nsAString& aName,
+                                             ErrorResult& aRv);
+
   DOMHighResTimeStamp ResolveEndTimeForMeasure(
       const Optional<nsAString>& aEndMark,
       const Maybe<const PerformanceMeasureOptions&>& aOptions,

testing/web-platform/meta/user-timing/performance-measure-invalid.worker.js.ini

@@ -1,4 +0,0 @@
-[performance-measure-invalid.worker.html]
-  [When converting 'navigationStart' to a timestamp, the global object has to be a Window object.]
-    expected: FAIL
-