Remove support in GPU backend for distance vector field.

Also, remvoes SkNormalBevelSource as this was the last use case for the distance vector field.

Change-Id: Ib0176c78e500e6b5130310934253a75860245812
Reviewed-on: https://skia-review.googlesource.com/18482
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/src/gpu/GrProcessorSet.h b/src/gpu/GrProcessorSet.h
index b13175a..d7ceced 100644
--- a/src/gpu/GrProcessorSet.h
+++ b/src/gpu/GrProcessorSet.h
@@ -52,8 +52,6 @@
         return sk_ref_sp(fXP.fProcessor);
     }
 
-    bool usesDistanceVectorField() const { return SkToBool(fFlags & kUseDistanceVectorField_Flag); }
-
     /** Comparisons are only legal on finalized processor sets. */
     bool operator==(const GrProcessorSet& that) const;
     bool operator!=(const GrProcessorSet& that) const { return !(*this == that); }
@@ -143,7 +141,7 @@
     // This absurdly large limit allows Analysis and this to pack fields together.
     static constexpr int kMaxColorProcessors = UINT8_MAX;
 
-    enum Flags : uint16_t { kUseDistanceVectorField_Flag = 0x1, kFinalized_Flag = 0x2 };
+    enum Flags : uint16_t { kFinalized_Flag = 0x1 };
 
     union XP {
         XP(const GrXPFactory* factory) : fFactory(factory) {}