Reland "Make GPU cache invalidation SkMessageBus messages go to one GrContext."

This is a reland of f4c5bb9aba485aa47c27b15905d81992b7cf4707

Original change's description:
> Make GPU cache invalidation SkMessageBus messages go to one GrContext.
> 
> Makes it so the template param to SkMessageBus must implement:
> bool shouldSend(uint32_t inboxID) const
> 
> Updates all GPU backend message types to only go to the GrContext that
> is adding a cache entry.
> 
> Bug: skia:
> Change-Id: I3e8a4eb90654b7b8ac57cac9fb508c0ef1d51058
> Reviewed-on: https://skia-review.googlesource.com/140220
> Reviewed-by: Robert Phillips <robertphillips@google.com>
> Reviewed-by: Jim Van Verth <jvanverth@google.com>

Bug: skia:
Change-Id: I8402bfe3ed0170c99936d47050458817030b473b
Reviewed-on: https://skia-review.googlesource.com/140801
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/include/gpu/GrResourceKey.h b/include/gpu/GrResourceKey.h
index 90b84d7..5e9bf1f 100644
--- a/include/gpu/GrResourceKey.h
+++ b/include/gpu/GrResourceKey.h
@@ -8,13 +8,13 @@
 #ifndef GrResourceKey_DEFINED
 #define GrResourceKey_DEFINED
 
+#include <new>
 #include "../private/SkOnce.h"
 #include "../private/SkTemplates.h"
 #include "../private/SkTo.h"
 #include "GrTypes.h"
 #include "SkData.h"
 #include "SkString.h"
-#include <new>
 
 uint32_t GrResourceKeyHash(const uint32_t* data, size_t size);
 
@@ -315,18 +315,22 @@
 // The cache listens for these messages to purge junk resources proactively.
 class GrUniqueKeyInvalidatedMessage {
 public:
-    explicit GrUniqueKeyInvalidatedMessage(const GrUniqueKey& key) : fKey(key) {}
-
-    GrUniqueKeyInvalidatedMessage(const GrUniqueKeyInvalidatedMessage& that) : fKey(that.fKey) {}
-
-    GrUniqueKeyInvalidatedMessage& operator=(const GrUniqueKeyInvalidatedMessage& that) {
-        fKey = that.fKey;
-        return *this;
+    GrUniqueKeyInvalidatedMessage(const GrUniqueKey& key, uint32_t contextUniqueID)
+            : fKey(key), fContextID(contextUniqueID) {
+        SkASSERT(SK_InvalidUniqueID != contextUniqueID);
     }
 
+    GrUniqueKeyInvalidatedMessage(const GrUniqueKeyInvalidatedMessage&) = default;
+
+    GrUniqueKeyInvalidatedMessage& operator=(const GrUniqueKeyInvalidatedMessage&) = default;
+
     const GrUniqueKey& key() const { return fKey; }
 
+    bool shouldSend(uint32_t inboxID) const { return fContextID == inboxID; }
+
 private:
     GrUniqueKey fKey;
+    uint32_t fContextID;
 };
+
 #endif