Correct the flag: is_extension_upgrade, which denote whether the extension is being upgrading.

chrome/browser/extensions/extension_service.cc

Index: chrome/browser/extensions/extension_service.cc
diff --git a/chrome/browser/extensions/extension_service.cc b/chrome/browser/extensions/extension_service.cc
index 5829a47b5f8c0f6e947b7878ecd302e859cced62..4587dcd8b3972170b4e7508aa5293a26563e8ba6 100644
--- a/chrome/browser/extensions/extension_service.cc
+++ b/chrome/browser/extensions/extension_service.cc
@@ -1996,13 +1996,16 @@ void ExtensionService::AddExtension(const Extension* extension) {
   }
 
   bool is_extension_upgrade = false;
-  if (const Extension* old = GetInstalledExtension(extension->id())) {
-    is_extension_upgrade = true;
-    DCHECK_NE(extension, old);

[zhchbin, 2013/07/30 01:53:56]

As my comment, this DCHECK_NE make no sense because the AddExtension will be
called in many code path. This line of code is copied without check before it's
committed. So I also remove it. https://chromiumcodereview.appspot.com/14490002

+  const Extension* old = GetInstalledExtension(extension->id());
+  if (old) {
     // Other than for unpacked extensions, CrxInstaller should have guaranteed
     // that we aren't downgrading.
-    if (!Manifest::IsUnpackedLocation(extension->location()))
-      CHECK_GE(extension->version()->CompareTo(*(old->version())), 0);
+    if (!Manifest::IsUnpackedLocation(extension->location())) {
+      int version_compare_result =
+          extension->version()->CompareTo(*(old->version()));
+      is_extension_upgrade = version_compare_result > 0;
+      CHECK_GE(version_compare_result, 0);
+    }
   }
   SetBeingUpgraded(extension, is_extension_upgrade);