PDF: remove unnecessary mutexes.

src/pdf/SkPDFStream.h

Index: src/pdf/SkPDFStream.h
diff --git a/src/pdf/SkPDFStream.h b/src/pdf/SkPDFStream.h
index cf9316ff1446d7af0288e844a6452fe68c90d3d5..90c6bcacb6aff97fdf1f502c78a633aaeaecb556 100644
--- a/src/pdf/SkPDFStream.h
+++ b/src/pdf/SkPDFStream.h
@@ -39,8 +39,7 @@ public:
 
     virtual ~SkPDFStream();
 
-    // The SkPDFObject interface.  This two method uses a mutex to
-    // allow multiple threads to call at the same time.
+    // The SkPDFObject interface.
     virtual void emitObject(SkWStream* stream, SkPDFCatalog* catalog) SK_OVERRIDE;
 
 protected:
@@ -90,9 +89,6 @@ private:
     // Indicates what form (or if) the stream has been requested.
     State fState;
 
-    // Mutex guards fState, fDataStream, and fSubstitute in public interface.
-    SkMutex fMutex;
-
     SkAutoTDelete<SkStreamRewindable> fDataStream;
     SkAutoTUnref<SkPDFStream> fSubstitute;