WebUI NTP: use local-ntp if DSP is not google

Third-party search providers may or may not have third-party NTPs. When
they do not have a third-party NTP, the local-ntp is used to display
the most-visited tiles.

Bug: 1087531
Change-Id: I799e252edba04e07601fc43938688cf1d381d183
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2225625Reviewed-by: Moe Ahmadi <mahmadi@chromium.org>
Commit-Queue: Moe Ahmadi <mahmadi@chromium.org>
Commit-Queue: Esmael Elmoslimany <aee@chromium.org>
Auto-Submit: Esmael Elmoslimany <aee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#774373}

chrome/browser/search/search.cc

@@ -178,7 +178,8 @@ struct NewTabURLDetails {
 #if defined(OS_ANDROID)
     const GURL local_url(chrome::kChromeSearchLocalNtpUrl);
 #else
-    const GURL local_url(base::FeatureList::IsEnabled(ntp_features::kWebUI)
+    const GURL local_url(base::FeatureList::IsEnabled(ntp_features::kWebUI) &&
+                                 DefaultSearchProviderIsGoogle(profile)
                              ? chrome::kChromeUINewTabPageURL
                              : chrome::kChromeSearchLocalNtpUrl);
 #endif