Respect Autocomplete setting for DSE preconnect

This adds a check to prevent DSE preconnect when the user has opted out
of DSE automplete and URL uploads.

Bug: 1036489
Change-Id: I015f4111377657193e6db99ca7bf2f809629270f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2028296Reviewed-by: Ryan Sturm <ryansturm@chromium.org>
Reviewed-by: Robert Ogden <robertogden@chromium.org>
Auto-Submit: Ryan Sturm <ryansturm@chromium.org>
Commit-Queue: Robert Ogden <robertogden@chromium.org>
Cr-Commit-Position: refs/heads/master@{#736947}

chrome/browser/navigation_predictor/search_engine_preconnector.cc

@@ -11,7 +11,9 @@
 #include "chrome/browser/predictors/loading_predictor_factory.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/search_engines/template_url_service_factory.h"
+#include "chrome/common/pref_names.h"
 #include "components/google/core/common/google_util.h"
+#include "components/prefs/pref_service.h"
 #include "components/search_engines/template_url_service.h"
 #include "content/public/browser/browser_context.h"
 #include "net/base/features.h"
@@ -61,6 +63,12 @@ void SearchEnginePreconnector::PreconnectDSE() {
   if (!base::FeatureList::IsEnabled(features::kPreconnectToSearch))
     return;
 
+  // Don't preconnect unless the user allows search suggestions.
+  if (!Profile::FromBrowserContext(browser_context_)
+           ->GetPrefs()
+           ->GetBoolean(prefs::kSearchSuggestEnabled))
+    return;
+
   GURL preconnect_url = GetDefaultSearchEngineOriginURL();
   if (preconnect_url.scheme() != url::kHttpScheme &&
       preconnect_url.scheme() != url::kHttpsScheme) {