Fix IndexedDB race condition during shutdown.

chrome/browser/in_process_webkit/indexed_db_key_utility_client.h

Index: chrome/browser/in_process_webkit/indexed_db_key_utility_client.h
diff --git a/chrome/browser/in_process_webkit/indexed_db_key_utility_client.h b/chrome/browser/in_process_webkit/indexed_db_key_utility_client.h
index 3a79c282be520b8bfa973c23b68d6a2eb96b9e04..cfdcd55f2b1975d075f76c0c711ad11cd57eb747 100644
--- a/chrome/browser/in_process_webkit/indexed_db_key_utility_client.h
+++ b/chrome/browser/in_process_webkit/indexed_db_key_utility_client.h
@@ -6,32 +6,26 @@
 #define CHROME_BROWSER_IN_PROCESS_WEBKIT_INDEXED_DB_KEY_UTILITY_CLIENT_H_
 #pragma once
 
+#include <vector>
+
 #include "base/ref_counted.h"
-#include "base/synchronization/waitable_event.h"
-#include "chrome/browser/utility_process_host.h"
+#include "base/singleton.h"
+#include "base/string16.h"
 
 class IndexedDBKey;
 class SerializedScriptValue;
+class KeyUtilityClientImpl;
 
-// This class is responsible to obtain IndexedDBKeys from the
-// SerializedScriptValues given an IDBKeyPath. It uses UtilityProcess to do this
-// inside a sandbox (a V8 lock is required there). At this level, all methods
-// are synchronous as required by the caller. The public API is used on
-// WEBKIT thread, but internally it moves around to UI and IO as needed.
-class IndexedDBKeyUtilityClient
-    : public base::RefCountedThreadSafe<IndexedDBKeyUtilityClient> {
+// Class for obtaining IndexedDBKeys from the SerializedScriptValues given
+// an IDBKeyPath. This class is a thin singleton wrapper around the
+// KeyUtilityClientImpl, which does the real work.
+class IndexedDBKeyUtilityClient {
  public:
-  IndexedDBKeyUtilityClient();
+  // Returns the singleton instance of the IndexedDBKeyUtilityClient.
+  static IndexedDBKeyUtilityClient* GetInstance();
 
-  // Starts the UtilityProcess. Must be called before any other method.
-  void StartUtilityProcess();
-
-  // Ends the UtilityProcess. Must be called after StartUtilityProcess() and
-  // before destruction.
-  // TODO(bulach): figure out an appropriate hook so that we can keep the
-  // UtilityProcess running for a longer period of time and avoid spinning it
-  // on every IDBObjectStore::Put call.
-  void EndUtilityProcess();
+  // Shut down the underlying implementation. Must be called on the IO thread.
+  void Shutdown();
 
   // Synchronously obtain the |keys| from |values| for the given |key_path|.
   void CreateIDBKeysFromSerializedValuesAndKeyPath(
@@ -40,53 +34,14 @@ class IndexedDBKeyUtilityClient
       std::vector<IndexedDBKey>* keys);
 
  private:
-  class Client : public UtilityProcessHost::Client {
-   public:
-    explicit Client(IndexedDBKeyUtilityClient* parent);
-
-    // UtilityProcessHost::Client
-    virtual void OnProcessCrashed(int exit_code);
-    virtual void OnIDBKeysFromValuesAndKeyPathSucceeded(
-        int id, const std::vector<IndexedDBKey>& keys);
-    virtual void OnIDBKeysFromValuesAndKeyPathFailed(int id);
-
-   private:
-    IndexedDBKeyUtilityClient* parent_;
-
-    DISALLOW_COPY_AND_ASSIGN(Client);
-  };
-
-  friend class base::RefCountedThreadSafe<IndexedDBKeyUtilityClient>;
+  friend struct DefaultSingletonTraits<IndexedDBKeyUtilityClient>;
+  IndexedDBKeyUtilityClient();
   ~IndexedDBKeyUtilityClient();
 
-  void GetRDHAndStartUtilityProcess();
-  void StartUtilityProcessInternal(ResourceDispatcherHost* rdh);
-  void EndUtilityProcessInternal();
-  void CallStartIDBKeyFromValueAndKeyPathFromIOThread(
-      const std::vector<SerializedScriptValue>& values,
-      const string16& key_path);
-
-  void SetKeys(const std::vector<IndexedDBKey>& keys);
-  void FinishCreatingKeys();
-
-  base::WaitableEvent waitable_event_;
-
-  // Used in both IO and WEBKIT threads, but guarded by WaitableEvent, i.e.,
-  // these members are only set / read when the other thread is blocked.
-  enum State {
-    STATE_UNINITIALIZED,
-    STATE_INITIALIZED,
-    STATE_CREATING_KEYS,
-    STATE_SHUTDOWN,
-  };
-  State state_;
-  std::vector<IndexedDBKey> keys_;
-
-  // Used in the IO thread.
-  UtilityProcessHost* utility_process_host_;
-  scoped_refptr<Client> client_;
+  bool is_shutdown_;
 
-  DISALLOW_COPY_AND_ASSIGN(IndexedDBKeyUtilityClient);
+  // The real client; laziliy instantiated.
+  scoped_refptr<KeyUtilityClientImpl> impl_;
 };
 
 #endif  // CHROME_BROWSER_IN_PROCESS_WEBKIT_INDEXED_DB_KEY_UTILITY_CLIENT_H_