[Tab Scrolling] Remove flex weight on the tab scrolling container.

This weight is not yet supported on flex layout.

Change-Id: I1feedb55eece8fa7b7a7d5a92d06021f051d2aaa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2429648
Auto-Submit: Charlene Yan <cyan@chromium.org>
Commit-Queue: Charlene Yan <cyan@chromium.org>
Commit-Queue: Dana Fried <dfried@chromium.org>
Reviewed-by: Dana Fried <dfried@chromium.org>
Cr-Commit-Position: refs/heads/master@{#810472}

chrome/browser/ui/views/frame/tab_strip_region_view.cc

@@ -39,8 +39,7 @@ TabStripRegionView::TabStripRegionView(std::unique_ptr<TabStrip> tab_strip) {
   const views::FlexSpecification tab_strip_container_flex_spec =
       views::FlexSpecification(views::LayoutOrientation::kHorizontal,
                                views::MinimumFlexSizeRule::kScaleToZero,
-                               views::MaximumFlexSizeRule::kUnbounded)
-          .WithWeight(0);
+                               views::MaximumFlexSizeRule::kUnbounded);
   tab_strip_container_->SetProperty(views::kFlexBehaviorKey,
                                     tab_strip_container_flex_spec);