Rename flag from "distance field" to "device independent."

Review URL: https://codereview.chromium.org/1322433006
diff --git a/dm/DMGpuSupport.h b/dm/DMGpuSupport.h
index 3b64bd8..0b9596e 100644
--- a/dm/DMGpuSupport.h
+++ b/dm/DMGpuSupport.h
@@ -29,8 +29,8 @@
                                        GrGLStandard gpuAPI,
                                        SkImageInfo info,
                                        int samples,
-                                       bool useDFText) {
-    uint32_t flags = useDFText ? SkSurfaceProps::kUseDistanceFieldFonts_Flag : 0;
+                                       bool useDIText) {
+    uint32_t flags = useDIText ? SkSurfaceProps::kUseDeviceIndependentFonts_Flag : 0;
     SkSurfaceProps props(flags, SkSurfaceProps::kLegacyFontHost_InitType);
     return SkSurface::NewRenderTarget(grFactory->get(type, gpuAPI), SkSurface::kNo_Budgeted,
                                       info, samples, &props);