Rename SkDescriptor::equals to SkDescriptor::operator==

BUG=chromium:608566
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1986253002

Review-Url: https://codereview.chromium.org/1986253002
diff --git a/src/core/SkDescriptor.h b/src/core/SkDescriptor.h
index 0f13acd..7360219 100644
--- a/src/core/SkDescriptor.h
+++ b/src/core/SkDescriptor.h
@@ -85,7 +85,7 @@
         return desc;
     }
 
-    bool equals(const SkDescriptor& other) const {
+    bool operator==(const SkDescriptor& other) const {
         // probe to see if we have a good checksum algo
 //        SkASSERT(a.fChecksum != b.fChecksum || memcmp(&a, &b, a.fLength) == 0);