Proactive SkPixelRef invalidation

src/gpu/GrResourceCache.h

Index: src/gpu/GrResourceCache.h
diff --git a/src/gpu/GrResourceCache.h b/src/gpu/GrResourceCache.h
index a9adf91b6f7216124c7b2e7f408def9b3b690200..38378ac77130ffdf45c522ef24ee9474d2aa0bb3 100644
--- a/src/gpu/GrResourceCache.h
+++ b/src/gpu/GrResourceCache.h
@@ -15,6 +15,7 @@
 #include "GrTypes.h"
 #include "GrTHashTable.h"
 #include "GrBinHashKey.h"
+#include "SkMessageBus.h"
 #include "SkTInternalLList.h"
 
 class GrResource;
@@ -141,6 +142,11 @@ private:
     Key fKey;
 };
 
+// The cache listens for these messages to purge junk resources proactively.
+struct GrResourceInvalidatedMessage {
+    GrResourceKey key;
+};
+
 ///////////////////////////////////////////////////////////////////////////////
 
 class GrResourceEntry {
@@ -395,6 +401,10 @@ private:
 
     void internalPurge(int extraCount, size_t extraBytes);
 
+    // Listen for messages that a resource has been invalidated and purge cached junk proactively.
+    SkMessageBus<GrResourceInvalidatedMessage>::Inbox fInvalidationInbox;
+    void purgeInvalidated();
+
 #ifdef SK_DEBUG
     static size_t countBytes(const SkTInternalLList<GrResourceEntry>& list);
 #endif