SkResourceCache::Key namespace support.

src/core/SkResourceCache.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkResourceCache_DEFINED
 #define SkResourceCache_DEFINED
 
@@ skipping 13 matching lines @@
  *  As a convenience, a global instance is also defined, which can be safely
  *  access across threads via the static methods (e.g. FindAndLock, etc.).
  */
 class SkResourceCache {
 public:
     struct Key {
         // Call this to access your private contents. Must not use the address after calling init()
         void* writableContents() { return this + 1; }
 
         // must call this after your private data has been written.
+        // nameSpace must be unique per Key subclass.
         // length must be a multiple of 4
-        void init(size_t length);
+        void init(void* nameSpace, size_t length);
 
         // This is only valid after having called init().
         uint32_t hash() const { return fHash; }
 
         bool operator==(const Key& other) const {
             const uint32_t* a = this->as32();
             const uint32_t* b = other.as32();
             for (int i = 0; i < fCount32; ++i) {  // (This checks fCount == other.fCount first.)
                 if (a[i] != b[i]) {
                     return false;
                 }
             }
             return true;
         }
 
     private:
-        int32_t  fCount32;  // 2 + user contents count32
+        int32_t  fCount32;   // local + user contents count32
         uint32_t fHash;
+        void*    fNamespace; // A unique namespace tag. This is hashed.
         /* uint32_t fContents32[] */
 
         const uint32_t* as32() const { return (const uint32_t*)this; }
     };
 
     struct Rec {
         typedef SkResourceCache::Key Key;
 
         Rec() {}
         virtual ~Rec() {}
@@ skipping 165 matching lines @@
 
     void init();    // called by constructors
 
 #ifdef SK_DEBUG
     void validate() const;
 #else
     void validate() const {}
 #endif
 };
 #endif