Bug 927349 part 7 - Factor out AnimationTimeline::GetRefreshDriver into a separate method; r=jwatt

This is in preparation for adding AnimationTimeline::FastForward in the next
patch which will reuse this code.

dom/animation/AnimationTimeline.cpp

@@ -55,17 +55,12 @@ AnimationTimeline::GetCurrentTimeStamp() const
     result = timing->GetNavigationStartTimeStamp();
   }
 
-  nsIPresShell* presShell = mDocument->GetShell();
-  if (MOZ_UNLIKELY(!presShell)) {
+  nsRefreshDriver* refreshDriver = GetRefreshDriver();
+  if (!refreshDriver) {
     return result;
   }
 
-  nsPresContext* presContext = presShell->GetPresContext();
-  if (MOZ_UNLIKELY(!presContext)) {
-    return result;
-  }
-
-  result = presContext->RefreshDriver()->MostRecentRefresh();
+  result = refreshDriver->MostRecentRefresh();
   // FIXME: We would like to assert that:
   //   mLastCurrentTime.IsNull() || result >= mLastCurrentTime
   // but due to bug 1043078 this will not be the case when the refresh driver
@@ -104,5 +99,21 @@ AnimationTimeline::ToTimeStamp(const TimeDuration& aTimeDuration) const
   return result;
 }
 
+nsRefreshDriver*
+AnimationTimeline::GetRefreshDriver() const
+{
+  nsIPresShell* presShell = mDocument->GetShell();
+  if (MOZ_UNLIKELY(!presShell)) {
+    return nullptr;
+  }
+
+  nsPresContext* presContext = presShell->GetPresContext();
+  if (MOZ_UNLIKELY(!presContext)) {
+    return nullptr;
+  }
+
+  return presContext->RefreshDriver();
+}
+
 } // namespace dom
 } // namespace mozilla

dom/animation/AnimationTimeline.h

@@ -14,6 +14,7 @@
 #include "nsIDocument.h"
 
 struct JSContext;
+class nsRefreshDriver;
 
 namespace mozilla {
 namespace dom {
@@ -26,6 +27,10 @@ public:
   {
   }
 
+protected:
+  virtual ~AnimationTimeline() { }
+
+public:
   NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(AnimationTimeline)
   NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_NATIVE_CLASS(AnimationTimeline)
 
@@ -47,8 +52,7 @@ public:
 
 protected:
   TimeStamp GetCurrentTimeStamp() const;
-
-  virtual ~AnimationTimeline() { }
+  nsRefreshDriver* GetRefreshDriver() const;
 
   nsCOMPtr<nsIDocument> mDocument;