Replace "external_install" boolean parameter with explicit enumeration in ExtensionUninstall method.

chrome/browser/themes/theme_service_unittest.cc

Index: chrome/browser/themes/theme_service_unittest.cc
diff --git a/chrome/browser/themes/theme_service_unittest.cc b/chrome/browser/themes/theme_service_unittest.cc
index cbebc923b8ffacb585e4c69c416f58c8d0f6a7cf..f9524eefe3ed7f7d917e086e4d5818b2eca00b6c 100644
--- a/chrome/browser/themes/theme_service_unittest.cc
+++ b/chrome/browser/themes/theme_service_unittest.cc
@@ -118,7 +118,8 @@ TEST_F(ThemeServiceTest, ThemeInstallUninstall) {
   EXPECT_EQ(extension_id, theme_service->GetThemeID());
 
   // Now uninstall the extension, should revert to the default theme.
-  service_->UninstallExtension(extension_id, false, NULL);
+  service_->UninstallExtension(
+      extension_id, ExtensionService::kUninstallReasonDefault, NULL);
   EXPECT_TRUE(theme_service->UsingDefaultTheme());
 }