Add factory class for generating various flavors of GrTextContext.

include/gpu/SkGpuDevice.h

Index: include/gpu/SkGpuDevice.h
diff --git a/include/gpu/SkGpuDevice.h b/include/gpu/SkGpuDevice.h
index 9b7129fbf6239a8aa1c09e7bfc953e45428c80f2..aa536089dd70e183cba8b083d1d4a4ce9250c409 100644
--- a/include/gpu/SkGpuDevice.h
+++ b/include/gpu/SkGpuDevice.h
@@ -16,10 +16,10 @@
 #include "SkBitmapDevice.h"
 #include "SkRegion.h"
 #include "GrContext.h"
+#include "GrTextContext.h"
 
 struct SkDrawProcs;
 struct GrSkDrawProcs;
-class GrTextContext;
 
 /**
  *  Subclass of SkBitmapDevice, which directs all drawing to the GrGpu owned by the
@@ -149,6 +149,8 @@ private:
 
     GrClipData      fClipData;
 
+    GrTextContextFactory* fTextContextFactory;
+
     // state for our render-target
     GrRenderTarget*     fRenderTarget;
     bool                fNeedClear;