Clean up threading model of external extension providers

chrome/browser/extensions/external_extension_provider_interface.h

Index: chrome/browser/extensions/external_extension_provider_interface.h
diff --git a/chrome/browser/extensions/external_extension_provider.h b/chrome/browser/extensions/external_extension_provider_interface.h
similarity index 58%
rename from chrome/browser/extensions/external_extension_provider.h
rename to chrome/browser/extensions/external_extension_provider_interface.h
index 5bcce1d5f4d7d150d3b50304038a204900330f5c..7f9d3c49996618771db8d6d19dd59eb7492a073a 100644
--- a/chrome/browser/extensions/external_extension_provider.h
+++ b/chrome/browser/extensions/external_extension_provider_interface.h
@@ -1,11 +1,14 @@
-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef CHROME_BROWSER_EXTENSIONS_EXTERNAL_EXTENSION_PROVIDER_H_
-#define CHROME_BROWSER_EXTENSIONS_EXTERNAL_EXTENSION_PROVIDER_H_
+#ifndef CHROME_BROWSER_EXTENSIONS_EXTERNAL_EXTENSION_PROVIDER_INTERFACE_H_
+#define CHROME_BROWSER_EXTENSIONS_EXTERNAL_EXTENSION_PROVIDER_INTERFACE_H_
 #pragma once
 
+#include <vector>
+
+#include "base/linked_ptr.h"
 #include "chrome/common/extensions/extension.h"
 
 class FilePath;
@@ -13,13 +16,13 @@ class Version;
 
 // This class is an abstract class for implementing external extensions
 // providers.
-class ExternalExtensionProvider {
+class ExternalExtensionProviderInterface {
  public:
   // ExternalExtensionProvider uses this interface to communicate back to the
   // caller what extensions are registered, and which |id|, |version| and |path|
   // they have. See also VisitRegisteredExtension below. Ownership of |version|
   // is not transferred to the visitor.
-  class Visitor {
+  class VisitorInterface {
    public:
      virtual void OnExternalExtensionFileFound(
          const std::string& id,
@@ -32,16 +35,23 @@ class ExternalExtensionProvider {
          const GURL& update_url,
          Extension::Location location) = 0;
 
+     // Called after all the external extensions have been reported through
+     // the above two methods.
+     virtual void OnExternalProviderReady() = 0;
+
    protected:
-     virtual ~Visitor() {}
+     virtual ~VisitorInterface() {}
   };
 
-  virtual ~ExternalExtensionProvider() {}
+  virtual ~ExternalExtensionProviderInterface() {}
+
+  // The visitor (ExtensionsService) calls this function before it goes away.
+  virtual void ServiceShutdown() = 0;
 
-  // Enumerate registered extension, calling OnExternalExtensionFound on
-  // the |visitor| object for each registered extension found. |ids_to_ignore|
-  // contains a list of extension ids that should not result in a call back.
-  virtual void VisitRegisteredExtension(Visitor* visitor) const = 0;
+  // Enumerate registered extensions, calling
+  // OnExternalExtension(File|UpdateUrl)Found on the |visitor| object for each
+  // registered extension found.
+  virtual void VisitRegisteredExtension() const = 0;
 
   // Test if this provider has an extension with id |id| registered.
   virtual bool HasExtension(const std::string& id) const = 0;
@@ -53,6 +63,13 @@ class ExternalExtensionProvider {
   virtual bool GetExtensionDetails(const std::string& id,
                                    Extension::Location* location,
                                    scoped_ptr<Version>* version) const = 0;
+
+  // Determines if this provider had loaded the list of external extensions
+  // from its source.
+  virtual bool IsReady() = 0;
 };
 
-#endif  // CHROME_BROWSER_EXTENSIONS_EXTERNAL_EXTENSION_PROVIDER_H_
+typedef std::vector<linked_ptr<ExternalExtensionProviderInterface> >
+    ProviderCollection;
+
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTERNAL_EXTENSION_PROVIDER_INTERFACE_H_