Enable NTP ZPS by default on iOS

The experiment has performed well at 50%, and we are ready to ramp to
100%.

Bug: 1056781
Change-Id: I17ff0d44e3b5a8ba5dcc54d7b520e7484890a1c4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2380656
Commit-Queue: Robbie Gibson <rkgibson@google.com>
Reviewed-by: Tommy Li <tommycli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813134}

components/omnibox/browser/zero_suggest_provider.cc

@@ -725,11 +725,10 @@ ZeroSuggestProvider::ResultType ZeroSuggestProvider::TypeOfResultToRun(
   if (base::Contains(field_trial_variants, kMostVisitedVariant))
     return MOST_VISITED;
 
-#if !defined(OS_IOS)
-  // For Desktop and Android, default to REMOTE_NO_URL on the NTP, if allowed.
+  // For Desktop, Android, and iOS, default to REMOTE_NO_URL on the NTP, if
+  // allowed.
   if (IsNTPPage(current_page_classification) && remote_no_url_allowed)
     return REMOTE_NO_URL;
-#endif
 
 #if defined(OS_ANDROID) || defined(OS_IOS)
   // For Android and iOS, default to MOST_VISITED everywhere except on the SERP.

components/omnibox/browser/zero_suggest_provider_unittest.cc

@@ -279,7 +279,7 @@ TEST_F(ZeroSuggestProviderTest, TypeOfResultToRun) {
                       ? ZeroSuggestProvider::ResultType::REMOTE_NO_URL
                       : ZeroSuggestProvider::ResultType::NONE,
                   result_type);
-#elif !defined(OS_IOS)  // Android
+#else                                         // Android and iOS
         EXPECT_EQ(BaseSearchProvider::IsNTPPage(current_page_classification) &&
                           remote_no_url_allowed
                       ? ZeroSuggestProvider::ResultType::REMOTE_NO_URL
@@ -288,12 +288,6 @@ TEST_F(ZeroSuggestProviderTest, TypeOfResultToRun) {
                             ? ZeroSuggestProvider::ResultType::MOST_VISITED
                             : ZeroSuggestProvider::ResultType::NONE,
                   result_type);
-#else                   // iOS
-        EXPECT_EQ(!BaseSearchProvider::IsSearchResultsPage(
-                      current_page_classification)
-                      ? ZeroSuggestProvider::ResultType::MOST_VISITED
-                      : ZeroSuggestProvider::ResultType::NONE,
-                  result_type);
 #endif
       };