Made it possible to tell whether an extension is being installed or updated.

chrome/common/extensions/extension.h

 // Copyright (c) 2013 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_COMMON_EXTENSIONS_EXTENSION_H_
 #define CHROME_COMMON_EXTENSIONS_EXTENSION_H_
 
 #include <algorithm>
 #include <iosfwd>
 #include <map>
@@ skipping 679 matching lines @@
 
   scoped_ptr<base::DictionaryValue> extension_manifest;
   std::string extension_id;
   base::FilePath extension_path;
   Manifest::Location extension_location;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ExtensionInfo);
 };
 
+struct InstalledExtensionInfo {
+  // The extension being installed - this should always be non-NULL.
+  const Extension* extension;
+
+  // Was the extension already installed? (If true, this means the extension is
+  // being updated.)
+  bool already_installed;

[benwells, 2013/05/02 01:40:08]

I think this is more clear if it is just called is_update.

[Matt Giuca, 2013/05/02 05:40:33]

Done.

+
+  InstalledExtensionInfo(const Extension* extension, bool already_installed);
+};
+
 struct UnloadedExtensionInfo {
   extension_misc::UnloadedExtensionReason reason;
 
   // Was the extension already disabled?
   bool already_disabled;
 
   // The extension being unloaded - this should always be non-NULL.
   const Extension* extension;
 
   UnloadedExtensionInfo(
@@ skipping 20 matching lines @@
 
   UpdatedExtensionPermissionsInfo(
       const Extension* extension,
       const PermissionSet* permissions,
       Reason reason);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_COMMON_EXTENSIONS_EXTENSION_H_