Replace "about:blank" URL with existing constant value

Change-Id: I40da6b31558c158b27db52a5aa24e9fa26747e35
Reviewed-on: https://chromium-review.googlesource.com/1062268
Commit-Queue: Marcin Wiącek <marcin@mwiacek.com>
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#559451}

chrome/android/java/src/org/chromium/chrome/browser/searchwidget/SearchActivity.java

@@ -36,6 +36,7 @@ import org.chromium.chrome.browser.tabmodel.TabModel.TabLaunchType;
 import org.chromium.chrome.browser.util.IntentUtils;
 import org.chromium.components.url_formatter.UrlFormatter;
 import org.chromium.content_public.browser.LoadUrlParams;
+import org.chromium.content_public.common.ContentUrlConstants;
 import org.chromium.ui.base.ActivityWindowAndroid;
 
 /** Queries the user's default search engine and shows autocomplete suggestions. */
@@ -154,7 +155,7 @@ public class SearchActivity extends AsyncInitializationActivity
                 null, null);
         mTab.initialize(WebContentsFactory.createWebContents(false, false), null,
                 new TabDelegateFactory(), false, false);
-        mTab.loadUrl(new LoadUrlParams("about:blank"));
+        mTab.loadUrl(new LoadUrlParams(ContentUrlConstants.ABOUT_BLANK_DISPLAY_URL));
 
         mSearchBoxDataProvider.onNativeLibraryReady(mTab);
         mSearchBox.onNativeLibraryReady();