Add support for Tab Search interactive UI tests

Bug: 1099917
Change-Id: I7e1f6a3eb3a90cf097839cf76778043c3adb2338
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2388711
Commit-Queue: Roman Arora <romanarora@chromium.org>
Reviewed-by: Thomas Lukaszewicz <tluk@chromium.org>
Reviewed-by: dpapad <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#807287}

chrome/test/data/webui/BUILD.gn

@@ -8,6 +8,7 @@ import("//chrome/test/base/js2gtest.gni")
 import("//chrome/test/include_js_tests.gni")
 import("//third_party/closure_compiler/compile_js.gni")
 import("//ui/webui/resources/tools/js_modulizer.gni")
+import("//ui/webui/webui_features.gni")
 import("./namespace_rewrites.gni")
 
 if (include_js_tests) {
@@ -27,6 +28,10 @@ if (include_js_tests) {
       "settings/cr_settings_v3_interactive_ui_tests.js",
     ]
 
+    if (enable_tab_search) {
+      sources += [ "tab_search/test/tab_search_interactive_ui_tests.js" ]
+    }
+
     gen_include_files = [
       "polymer_browser_test_base.js",
       "polymer_interactive_ui_test.js",