Move ".crx"/".pem" constants and extension_filenames constants into extensions/common/constants.cc.

chrome/installer/setup/uninstall.cc

Index: chrome/installer/setup/uninstall.cc
diff --git a/chrome/installer/setup/uninstall.cc b/chrome/installer/setup/uninstall.cc
index 2d865350d41211b6fb4864fbef8376ef8cda0689..50b9ff82554f4313417ab000d5f6b897251d8b19 100644
--- a/chrome/installer/setup/uninstall.cc
+++ b/chrome/installer/setup/uninstall.cc
@@ -45,6 +45,7 @@
 #include "chrome/installer/util/shell_util.h"
 #include "chrome/installer/util/util_constants.h"
 #include "content/public/common/result_codes.h"
+#include "extensions/common/constants.h"
 #include "rlz/lib/rlz_lib.h"
 
 // Build-time generated include file.
@@ -908,7 +909,7 @@ const wchar_t kChromeExtProgId[] = L"ChromiumExt";
     // Delete Software\Classes\.crx,
     string16 ext_association(ShellUtil::kRegClasses);
     ext_association.append(L"\\");
-    ext_association.append(chrome::kExtensionFileExtension);
+    ext_association.append(extensions::kExtensionFileExtension);
     InstallUtil::DeleteRegistryKey(roots[i], ext_association);
   }
 }