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

chrome/common/extensions/extension.cc

Index: chrome/common/extensions/extension.cc
diff --git a/chrome/common/extensions/extension.cc b/chrome/common/extensions/extension.cc
index c4c1d9a2914762c2dfff9c6ff2a10224d6c1403f..c38abb886bd9c229f5184bd0c002deb8ee50fddd 100644
--- a/chrome/common/extensions/extension.cc
+++ b/chrome/common/extensions/extension.cc
@@ -1741,6 +1741,12 @@ ExtensionInfo::ExtensionInfo(const DictionaryValue* manifest,
 
 ExtensionInfo::~ExtensionInfo() {}
 
+InstalledExtensionInfo::InstalledExtensionInfo(
+    const Extension* extension,
+    bool already_installed)
+  : extension(extension),
+    already_installed(already_installed) {}
+
 UnloadedExtensionInfo::UnloadedExtensionInfo(
     const Extension* extension,
     extension_misc::UnloadedExtensionReason reason)