Dispatch IndexedDB IPC messages to worker threads

content/renderer/indexed_db_dispatcher.h

Index: content/renderer/indexed_db_dispatcher.h
diff --git a/content/renderer/indexed_db_dispatcher.h b/content/renderer/indexed_db_dispatcher.h
index d2b3f1aa95953f5545e1b2755aceaeb6e66a840c..8e3392bf5fa468c4390706994b12691b29a34d72 100644
--- a/content/renderer/indexed_db_dispatcher.h
+++ b/content/renderer/indexed_db_dispatcher.h
@@ -11,6 +11,8 @@
 
 #include "base/id_map.h"
 #include "base/nullable_string16.h"
+#include "content/common/child_thread.h"
+#include "content/renderer/indexed_db_message_filter.h"
 #include "ipc/ipc_channel.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebExceptionCode.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebIDBCallbacks.h"
@@ -32,13 +34,12 @@ class SerializedScriptValue;
 }
 
 // Handle the indexed db related communication for this entire renderer.
-class IndexedDBDispatcher : public IPC::Channel::Listener {
+class IndexedDBDispatcher {
  public:
-  IndexedDBDispatcher();
+  IndexedDBDispatcher(IndexedDBMessageFilter*);
   virtual ~IndexedDBDispatcher();
 
-  // IPC::Channel::Listener implementation.
-  virtual bool OnMessageReceived(const IPC::Message& msg) OVERRIDE;
+  void OnMessageReceived(const IPC::Message& msg);
   void Send(IPC::Message* msg);
 
   void RequestIDBFactoryGetDatabaseNames(
@@ -185,13 +186,47 @@ class IndexedDBDispatcher : public IPC::Channel::Listener {
   void OnComplete(int32 transaction_id);
   void OnVersionChange(int32 database_id, const string16& newVersion);
 
+  // This class facilitates mapping callback ids specified in incoming IPC
+  // messages to threads.  It:
+  // * Retrieves process-unique ids for each stored WebIDBCallbacks object.  The
+  //   browser process includes these ids in messages sent back to us.
+  // * Registers incoming transaction and database callback ids that are created
+  //   in the browser process.  We'll need to revisit this scheme if the browser
+  //   stops generating unique ids.
+  // * Ensures, through IDMap, that it is only called on a single thread.
+  template<class CallbackType>
+  class CallbackIDMap {
+   public:
+    CallbackIDMap(IndexedDBMessageFilter* filter) : filter_(filter) {
+    }
+    void AddWithID(CallbackType* callbacks, int32 id) {
+      filter_->NotifyAddWithIDForType(id, callbacks);
+      map_.AddWithID(callbacks, id);
+    }
+    int32 Add(CallbackType* callbacks) {
+      int id = filter_->GetUniqueID();
+      map_.AddWithID(callbacks, id);
+      return id;
+    }
+    void Remove(int32 id) {
+      filter_->RemoveForType(id, (CallbackType*)NULL);
+      map_.Remove(id);
+    }
+    CallbackType* Lookup(int32 id) {
+      return map_.Lookup(id);
+    }
+   private:
+    // The filter is alive for the life of the process, nothing deletes it.
+    IndexedDBMessageFilter* filter_;
+    IDMap<CallbackType, IDMapOwnPointer> map_;
+  };
+
   // Careful! WebIDBCallbacks wraps non-threadsafe data types. It must be
   // destroyed and used on the same thread it was created on.
-  IDMap<WebKit::WebIDBCallbacks, IDMapOwnPointer> pending_callbacks_;
-  IDMap<WebKit::WebIDBTransactionCallbacks, IDMapOwnPointer>
+  CallbackIDMap<WebKit::WebIDBCallbacks> pending_callbacks_;
+  CallbackIDMap<WebKit::WebIDBTransactionCallbacks>
       pending_transaction_callbacks_;
-  IDMap<WebKit::WebIDBDatabaseCallbacks, IDMapOwnPointer>
-      pending_database_callbacks_;
+  CallbackIDMap<WebKit::WebIDBDatabaseCallbacks> pending_database_callbacks_;
 
   // Map from cursor id to RendererWebIDBCursorImpl.
   std::map<int32, RendererWebIDBCursorImpl*> cursors_;