ccpr: Use SkMessageBus for thread-safe eviction of cache entries

Bug: skia:
Change-Id: I87725b95761deb689333315ce681a4968d98190a
Reviewed-on: https://skia-review.googlesource.com/c/163511
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
diff --git a/include/gpu/GrResourceKey.h b/include/gpu/GrResourceKey.h
index a125006..fb1b892 100644
--- a/include/gpu/GrResourceKey.h
+++ b/include/gpu/GrResourceKey.h
@@ -348,12 +348,16 @@
     GrUniqueKeyInvalidatedMessage& operator=(const GrUniqueKeyInvalidatedMessage&) = default;
 
     const GrUniqueKey& key() const { return fKey; }
-
-    bool shouldSend(uint32_t inboxID) const { return fContextID == inboxID; }
+    uint32_t contextID() const { return fContextID; }
 
 private:
     GrUniqueKey fKey;
     uint32_t fContextID;
 };
 
+static inline bool SkShouldPostMessageToBus(
+        const GrUniqueKeyInvalidatedMessage& msg, uint32_t msgBusUniqueID) {
+    return msg.contextID() == msgBusUniqueID;
+}
+
 #endif