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/tools/PictureRenderer.h b/tools/PictureRenderer.h
index e82eb7f..c8462d9 100644
--- a/tools/PictureRenderer.h
+++ b/tools/PictureRenderer.h
@@ -220,6 +220,10 @@
     void setSampleCount(int sampleCount) {
         fSampleCount = sampleCount;
     }
+
+    void setUseDFText(bool useDFText) {
+        fUseDFText = useDFText;
+    }
 #endif
 
     void setDrawFilters(DrawFilterFlags const * const filters, const SkString& configName) {
@@ -274,6 +278,8 @@
             case kGPU_DeviceType:
                 if (fSampleCount) {
                     config.appendf("_msaa%d", fSampleCount);
+                } else if (fUseDFText) {
+                    config.append("_gpudft");
                 } else {
                     config.append("_gpu");
                 }
@@ -325,6 +331,8 @@
                     tmp = "msaa";
                     tmp.appendS32(fSampleCount);
                     result["config"] = tmp.c_str();
+                } else if (fUseDFText) {
+                    result["config"] = "gpudft";
                 } else {
                     result["config"] = "gpu";
                 }
@@ -428,6 +436,7 @@
         , fGrContextFactory(opts)
         , fGrContext(NULL)
         , fSampleCount(0)
+        , fUseDFText(false)
 #endif
         {
             fGridInfo.fMargin.setEmpty();
@@ -495,6 +504,7 @@
     GrContextFactory       fGrContextFactory;
     GrContext*             fGrContext;
     int                    fSampleCount;
+    bool                   fUseDFText;
 #endif
 
     virtual SkString getConfigNameInternal() = 0;