o Cleans up canonical extension_install_ui.cc to avoid #ifdefs when feasible....

chrome/browser/views/extensions/extension_install_prompt.cc

Index: chrome/browser/views/extensions/extension_install_prompt.cc
===================================================================
--- chrome/browser/views/extensions/extension_install_prompt.cc	(revision 30026)
+++ chrome/browser/views/extensions/extension_install_prompt.cc	(working copy)
@@ -19,6 +19,10 @@
 #include "views/window/dialog_delegate.h"
 #include "views/window/window.h"
 
+#if defined(OS_WIN)
+#include "app/win_util.h"
+#endif
+
 class Profile;
 
 namespace {
@@ -134,7 +138,7 @@
   DISALLOW_COPY_AND_ASSIGN(InstallDialogContent);
 };
 
-} // namespace
+}  // namespace
 
 void ExtensionInstallUI::ShowExtensionInstallPrompt(
     Profile* profile, Delegate* delegate, Extension* extension, SkBitmap* icon,
@@ -155,3 +159,14 @@
       new InstallDialogContent(delegate, extension, icon,
                                warning_text))->Show();
 }
+
+void ExtensionInstallUI::ShowExtensionInstallError(const std::string& error) {
+#if defined(OS_WIN)
+  win_util::MessageBox(NULL, UTF8ToWide(error),
+      l10n_util::GetString(IDS_EXTENSION_INSTALL_FAILURE_TITLE),
+      MB_OK | MB_SETFOREGROUND);
+#else
+  // TODO(port): Port this over to OS_*
+  NOTREACHED();
+#endif
+}