Rename flushForExternalRead->flushForExternalIO and always call in SkSurface::getTextureHandle

include/gpu/GrSurface.h

Index: include/gpu/GrSurface.h
diff --git a/include/gpu/GrSurface.h b/include/gpu/GrSurface.h
index 543ccd134f09edc5e744c8ec8f4f493b2f44b155..bdf48be0f9b523e94ec63c699f18ff071a01a257 100644
--- a/include/gpu/GrSurface.h
+++ b/include/gpu/GrSurface.h
@@ -116,10 +116,10 @@ public:
 
 
     /**
-     * After this returns any pending writes to the surface will be issued to the backend 3D API and
+     * After this returns any pending surface IO will be issued to the backend 3D API and
      * if the surface has MSAA it will be resolved.
      */
-    void prepareForExternalRead();
+    void prepareForExternalIO();
 
     /** Access methods that are only to be used within Skia code. */
     inline GrSurfacePriv surfacePriv();