Add a variation for "New tab" in GTS

Have a different top toolbar layout for GTS when there are no open
incognito tabs. This is now behind #enable-tab-grid-layout with
parameter "Enable New Tab Variation".

Bug: 974079
Change-Id: I8aa972a64efa77a7cdad64b7481b45722d2e3132
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1659848
Commit-Queue: Yue Zhang <[email protected]>
Reviewed-by: Theresa <[email protected]>
Reviewed-by: Yusuf Ozuysal <[email protected]>
Cr-Commit-Position: refs/heads/master@{#670731}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index bb6e5d5..b79a4cd 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -995,6 +995,16 @@
 };
 #endif  // OS_ANDROID
 
+#if defined(OS_ANDROID)
+const FeatureEntry::FeatureParam kTabGridLayoutAndroid_NewTabVariation[] = {
+    {"tab_grid_layout_android_new_tab", "NewTabVariation"}};
+
+const FeatureEntry::FeatureVariation kTabGridLayoutAndroidVariations[] = {
+    {"New Tab Variation", kTabGridLayoutAndroid_NewTabVariation,
+     base::size(kTabGridLayoutAndroid_NewTabVariation), nullptr},
+};
+#endif  // OS_ANDROID
+
 const FeatureEntry::FeatureParam kVizHitTestDrawQuadEnabled[] = {
     {"provider", "draw_quad"}};
 
@@ -2966,7 +2976,9 @@
 
     {"enable-tab-grid-layout", flag_descriptions::kTabGridLayoutAndroidName,
      flag_descriptions::kTabGridLayoutAndroidDescription, kOsAndroid,
-     FEATURE_VALUE_TYPE(chrome::android::kTabGridLayoutAndroid)},
+     FEATURE_WITH_PARAMS_VALUE_TYPE(chrome::android::kTabGridLayoutAndroid,
+                                    kTabGridLayoutAndroidVariations,
+                                    "TabGridLayoutAndroid")},
 
     {"enable-tab-groups", flag_descriptions::kTabGroupsAndroidName,
      flag_descriptions::kTabGroupsAndroidDescription, kOsAndroid,