Minor GrContext/GrInOrderDrawBuffer cleanup

src/gpu/GrInOrderDrawBuffer.h

Index: src/gpu/GrInOrderDrawBuffer.h
===================================================================
--- src/gpu/GrInOrderDrawBuffer.h	(revision 9893)
+++ src/gpu/GrInOrderDrawBuffer.h	(working copy)
@@ -63,13 +63,9 @@
      * is destructive). This buffer must not have an active reserved vertex or index source. Any
      * reserved geometry on the target will be finalized because it's geometry source will be pushed
      * before flushing and popped afterwards.
-     *
-     * @return false if the playback trivially drew nothing because nothing was recorded.
      */
-    bool flush();
+    void flush();
 
-    bool isFlushing() const { return fFlushing; }
-
     // overrides from GrDrawTarget
     virtual bool geometryHints(int* vertexCount,
                                int* indexCount) const SK_OVERRIDE;