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 85bf1260b3236345297a2132d27a868d8e301b14..b0c2754f9e2e193b4c6097ae21ced2f156954ae2 100644
--- a/chrome/browser/themes/theme_service_unittest.cc
+++ b/chrome/browser/themes/theme_service_unittest.cc
@@ -119,7 +119,8 @@ 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::UNINSTALL_REASON_DEFAULT, NULL);
   EXPECT_TRUE(theme_service->UsingDefaultTheme());
 }