Bug 1571530 - Move Loader::Sheets out of line. r=heycam

I'm going to tweak it a bit.

Differential Revision: https://phabricator.services.mozilla.com/D40687

--HG--
extra : moz-landing-system : lando

layout/style/Loader.cpp

@@ -352,6 +352,16 @@ bool LoaderReusableStyleSheets::FindReusableStyleSheet(
   return false;
 }
 
+// A struct keeping alive various records of sheets that are loading, deferred,
+// or already loaded (the later one for caching purposes).
+struct Loader::Sheets {
+  nsBaseHashtable<SheetLoadDataHashKey, RefPtr<StyleSheet>, StyleSheet*>
+      mCompleteSheets;
+  // The SheetLoadData pointers below are weak references.
+  nsDataHashtable<SheetLoadDataHashKey, SheetLoadData*> mLoadingDatas;
+  nsDataHashtable<SheetLoadDataHashKey, SheetLoadData*> mPendingDatas;
+};
+
 /*************************
  * Loader Implementation *
  *************************/

layout/style/Loader.h

@@ -517,16 +517,7 @@ class Loader final {
   // directly or indirectly @importing the sheet this SheetLoadData represents.
   void MarkLoadTreeFailed(SheetLoadData* aLoadData);
 
-  struct Sheets {
-    nsBaseHashtable<SheetLoadDataHashKey, RefPtr<StyleSheet>, StyleSheet*>
-        mCompleteSheets;
-    nsDataHashtable<SheetLoadDataHashKey,
-                    SheetLoadData*>
-        mLoadingDatas;  // weak refs
-    nsDataHashtable<SheetLoadDataHashKey,
-                    SheetLoadData*>
-        mPendingDatas;  // weak refs
-  };
+  struct Sheets;
   UniquePtr<Sheets> mSheets;
 
   // The array of posted stylesheet loaded events (SheetLoadDatas) we have.