Support multiple HRTFDatabases for different sample-rates

Source/core/platform/audio/HRTFDatabaseLoader.h

Index: Source/core/platform/audio/HRTFDatabaseLoader.h
diff --git a/Source/core/platform/audio/HRTFDatabaseLoader.h b/Source/core/platform/audio/HRTFDatabaseLoader.h
index 4562db7665e52b54512937aaab2486f5484cf62d..701ddb35862383c6ddd2bba5a7309310fd33c4b2 100644
--- a/Source/core/platform/audio/HRTFDatabaseLoader.h
+++ b/Source/core/platform/audio/HRTFDatabaseLoader.h
@@ -30,10 +30,11 @@
 #define HRTFDatabaseLoader_h
 
 #include "core/platform/audio/HRTFDatabase.h"
-#include <wtf/PassRefPtr.h>
-#include <wtf/RefCounted.h>
-#include <wtf/RefPtr.h>
-#include <wtf/Threading.h>
+#include "wtf/HashMap.h"
+#include "wtf/PassRefPtr.h"
+#include "wtf/RefCounted.h"
+#include "wtf/RefPtr.h"
+#include "wtf/Threading.h"
 
 namespace WebCore {
 
@@ -41,14 +42,12 @@ namespace WebCore {
 
 class HRTFDatabaseLoader : public RefCounted<HRTFDatabaseLoader> {
 public:
-    // Lazily creates the singleton HRTFDatabaseLoader (if not already created) and starts loading asynchronously (when created the first time).
-    // Returns the singleton HRTFDatabaseLoader.
+    // Lazily creates a HRTFDatabaseLoader (if not already created) for the given sample-rate
+    // and starts loading asynchronously (when created the first time).
+    // Returns the HRTFDatabaseLoader.
     // Must be called from the main thread.
     static PassRefPtr<HRTFDatabaseLoader> createAndLoadAsynchronouslyIfNecessary(float sampleRate);
 
-    // Returns the singleton HRTFDatabaseLoader.
-    static HRTFDatabaseLoader* loader() { return s_loader; }
-    
     // Both constructor and destructor must be called from the main thread.
     ~HRTFDatabaseLoader();
     
@@ -65,13 +64,16 @@ public:
     // Called in asynchronous loading thread.
     void load();
 
-    // defaultHRTFDatabase() gives access to the loaded database.
-    // This can be called from any thread, but it is the callers responsibilty to call this while the context (and thus HRTFDatabaseLoader)
-    // is still alive.  Otherwise this will return 0.
-    static HRTFDatabase* defaultHRTFDatabase();
-
     void reportMemoryUsage(MemoryObjectInfo*) const;
 
+    // Map from sample-rate to loader.
+    class LoaderMap : public HashMap<double, HRTFDatabaseLoader*> {
+    public:
+        void reportMemoryUsage(MemoryObjectInfo*) const;
+    };
+
+    static HRTFDatabaseLoader::LoaderMap* loaderMap() { return s_loaderMap; }
+
 private:
     // Both constructor and destructor must be called from the main thread.
     explicit HRTFDatabaseLoader(float sampleRate);
@@ -80,7 +82,9 @@ private:
     // This must be called from the main thread.
     void loadAsynchronously();
 
-    static HRTFDatabaseLoader* s_loader; // singleton
+    // Keeps track of loaders on a per-sample-rate basis.
+    static LoaderMap* s_loaderMap; // singleton
+
     OwnPtr<HRTFDatabase> m_hrtfDatabase;
 
     // Holding a m_threadLock is required when accessing m_databaseLoaderThread.