Add flag for SkGpuSurface creation to enable distance fields.

src/gpu/SkGpuDevice.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkGpuDevice.h"
 
 #include "effects/GrBicubicEffect.h"
@@ skipping 172 matching lines @@
 }
 
 void SkGpuDevice::initFromRenderTarget(GrContext* context,
                                        GrRenderTarget* renderTarget,
                                        unsigned flags) {
     fDrawProcs = NULL;
 
     fContext = context;
     fContext->ref();
 
-    fMainTextContext = SkNEW_ARGS(GrDistanceFieldTextContext, (fContext, fLeakyProperties));
+    bool useDFFonts = !!(flags & kDFFonts_Flag);
+    fMainTextContext = SkNEW_ARGS(GrDistanceFieldTextContext, (fContext, fLeakyProperties,
+                                                               useDFFonts));
     fFallbackTextContext = SkNEW_ARGS(GrBitmapTextContext, (fContext, fLeakyProperties));
 
     fRenderTarget = NULL;
     fNeedClear = flags & kNeedClear_Flag;
 
     SkASSERT(NULL != renderTarget);
     fRenderTarget = renderTarget;
     fRenderTarget->ref();
 
     // Hold onto to the texture in the pixel ref (if there is one) because the texture holds a ref
@@ skipping 1794 matching lines @@
             const GrCachedLayer* layer = fContext->getLayerCache()->findLayerOrCreate(picture, i);
 
             SkDebugf("%d (%d), ", i, layer->layerID());
         }
     }
     SkDebugf("\n");
 #endif
 
     return false;
 }