Add Gr*Proxy classes

include/core/SkTypes.h

Index: include/core/SkTypes.h
diff --git a/include/core/SkTypes.h b/include/core/SkTypes.h
index f9d0c533d3348400899734772301319f046a80d7..f99bb019498a5c15db390d668f34f67fb5811df9 100644
--- a/include/core/SkTypes.h
+++ b/include/core/SkTypes.h
@@ -442,6 +442,15 @@ enum class SkBudgeted : bool {
     kYes = true
 };
 
+/**
+ * Indicates whether a backing store needs to be an exact match or can be larger
+ * than is strictly necessary
+ */
+enum class SkBackingFit {
+    kApprox,
+    kExact
+};
+
 ///////////////////////////////////////////////////////////////////////////////
 
 /** Use to combine multiple bits in a bitmask in a type safe way.