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

chrome/common/extensions/extension.h

Index: chrome/common/extensions/extension.h
diff --git a/chrome/common/extensions/extension.h b/chrome/common/extensions/extension.h
index 10b143023e91713896440f3ee62abf76bd1a9949..4f8674c7dbe6072642cbe72cb4bec7b0620d139a 100644
--- a/chrome/common/extensions/extension.h
+++ b/chrome/common/extensions/extension.h
@@ -697,6 +697,16 @@ struct ExtensionInfo {
   DISALLOW_COPY_AND_ASSIGN(ExtensionInfo);
 };
 
+struct InstalledExtensionInfo {
+  // The extension being installed - this should always be non-NULL.
+  const Extension* extension;
+
+  // True if the extension is being updated; false if it is being installed.
+  bool is_update;
+
+  InstalledExtensionInfo(const Extension* extension, bool is_update);
+};
+
 struct UnloadedExtensionInfo {
   extension_misc::UnloadedExtensionReason reason;