Get gpudft support working in dm, gm, nanobench and bench_pictures

Adds a new config to test distance field text.
Clean up some flags and #defines to read "distance field text",
not "distance field fonts" to be consistent with Chromium

NOTREECHECKS=true

Committed: https://skia.googlesource.com/skia/+/06ba179838ba4fe187cf290750aeeb4a02a2960b

Review URL: https://codereview.chromium.org/699453005
diff --git a/src/gpu/SkGpuDevice.h b/src/gpu/SkGpuDevice.h
index 6a68eeb..6bba974 100644
--- a/src/gpu/SkGpuDevice.h
+++ b/src/gpu/SkGpuDevice.h
@@ -34,7 +34,7 @@
 public:
     enum Flags {
         kNeedClear_Flag = 1 << 0,  //!< Surface requires an initial clear
-        kDFFonts_Flag   = 1 << 1,  //!< Surface should render fonts using signed distance fields
+        kDFText_Flag   = 1 << 1,  //!< Surface should render text using signed distance fields
     };
 
     /**
@@ -136,8 +136,8 @@
     GrTextContext*  fTextContext;
 
     // state for our render-target
-    GrRenderTarget*     fRenderTarget;
-    bool                fNeedClear;
+    GrRenderTarget* fRenderTarget;
+    uint32_t        fFlags;
 
     // remove when our clients don't rely on accessBitmap()
     SkBitmap fLegacyBitmap;