RC: Enable TabLoadTracker unit tests on Android

TabLoadTracker unit tests were enabled only on non-Android platforms,
but TabLoadTracker is included on Android builds.

Bug: 861800
Change-Id: I571298a10dbc5113aaabde47a8288ad675c87e8b
Reviewed-on: https://chromium-review.googlesource.com/1129461Reviewed-by: Chris Hamilton <chrisha@chromium.org>
Commit-Queue: Scott Haseley <shaseley@google.com>
Cr-Commit-Position: refs/heads/master@{#584469}

chrome/test/BUILD.gn

@@ -2634,6 +2634,7 @@ test("unit_tests") {
     "../browser/push_messaging/push_messaging_notification_manager_unittest.cc",
     "../browser/push_messaging/push_messaging_service_unittest.cc",
     "../browser/renderer_host/chrome_render_widget_host_view_mac_history_swiper_unit_test.mm",
+    "../browser/resource_coordinator/tab_load_tracker_unittest.cc",
     "../browser/resources_util_unittest.cc",
     "../browser/search/contextual_search_policy_handler_android_unittest.cc",
     "../browser/search/thumbnail_source_unittest.cc",
@@ -3062,7 +3063,6 @@ test("unit_tests") {
       "../browser/resource_coordinator/tab_activity_watcher_unittest.cc",
       "../browser/resource_coordinator/tab_lifecycle_unit_source_unittest.cc",
       "../browser/resource_coordinator/tab_lifecycle_unit_unittest.cc",
-      "../browser/resource_coordinator/tab_load_tracker_unittest.cc",
       "../browser/resource_coordinator/tab_manager_delegate_chromeos_unittest.cc",
       "../browser/resource_coordinator/tab_manager_features_unittest.cc",
       "../browser/resource_coordinator/tab_manager_stats_collector_unittest.cc",