Add GrPrimitiveType::kLinesAdjacency

Converts GrPrimitiveType to an enum class and adds kLinesAdjacency.

Bug: skia:
Change-Id: I3b5e68acfb20476f6c6923968f5a4ac4f73ae12d
Reviewed-on: https://skia-review.googlesource.com/19680
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
diff --git a/src/gpu/SkGr.h b/src/gpu/SkGr.h
index 7232c80..090a384 100644
--- a/src/gpu/SkGr.h
+++ b/src/gpu/SkGr.h
@@ -165,14 +165,14 @@
 static inline GrPrimitiveType SkVertexModeToGrPrimitiveType(SkVertices::VertexMode mode) {
     switch (mode) {
         case SkVertices::kTriangles_VertexMode:
-            return kTriangles_GrPrimitiveType;
+            return GrPrimitiveType::kTriangles;
         case SkVertices::kTriangleStrip_VertexMode:
-            return kTriangleStrip_GrPrimitiveType;
+            return GrPrimitiveType::kTriangleStrip;
         case SkVertices::kTriangleFan_VertexMode:
-            return kTriangleFan_GrPrimitiveType;
+            return GrPrimitiveType::kTriangleFan;
     }
     SkFAIL("Invalid mode");
-    return kPoints_GrPrimitiveType;
+    return GrPrimitiveType::kPoints;
 }
 
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