Bug 1267568 part 2 - Add helper method to nsIPresShell to get the RefreshDriver. r=smaug

MozReview-Commit-ID: Cxbmr2CVXJz

--HG--
extra : source : fbf8cd895abbb69d3b5d3c2b3afe36984db5f985

layout/base/nsIPresShell.h

@@ -316,6 +316,8 @@ public:
 
   nsViewManager* GetViewManager() const { return mViewManager; }
 
+  nsRefreshDriver* GetRefreshDriver() const;
+
 #ifdef ACCESSIBILITY
   /**
    * Return the document accessible for this pres shell if there is one.

layout/base/nsPresShell.cpp

@@ -1340,6 +1340,12 @@ PresShell::MakeZombie()
   CancelAllPendingReflows();
 }
 
+nsRefreshDriver*
+nsIPresShell::GetRefreshDriver() const
+{
+  return mPresContext ? mPresContext->RefreshDriver() : nullptr;
+}
+
 void
 nsIPresShell::SetAuthorStyleDisabled(bool aStyleDisabled)
 {