GTK: Move to gtk_widget_get_allocation() for some of chrome/browser/ui/gtk/

chrome/browser/ui/gtk/tabs/tab_strip_gtk.cc

Index: chrome/browser/ui/gtk/tabs/tab_strip_gtk.cc
diff --git a/chrome/browser/ui/gtk/tabs/tab_strip_gtk.cc b/chrome/browser/ui/gtk/tabs/tab_strip_gtk.cc
index 1edc5adf3355f7ca03695bfec8d4a9ff77322cc2..272d741857345cd1dae210827a65d5e3d0211562 100644
--- a/chrome/browser/ui/gtk/tabs/tab_strip_gtk.cc
+++ b/chrome/browser/ui/gtk/tabs/tab_strip_gtk.cc
@@ -1451,7 +1451,7 @@ void TabStripGtk::LayoutNewTabButton(double last_tab_right,
     // We're shrinking tabs, so we need to anchor the New Tab button to the
     // right edge of the TabStrip's bounds, rather than the right edge of the
     // right-most Tab, otherwise it'll bounce when animating.
-    bounds.set_x(bounds_.width() - newtab_button_->width());
+    bounds.set_x(bounds_.width() - newtab_button_->WidgetWidth());
   } else {
     bounds.set_x(Round(last_tab_right - kTabHOffset) + kNewTabButtonHOffset);
   }
@@ -1486,7 +1486,7 @@ void TabStripGtk::GetDesiredTabWidths(int tab_count,
   if (available_width_for_tabs_ < 0) {
     available_width = bounds_.width();
     available_width -=
-        (kNewTabButtonHOffset + newtab_button_->width());
+        (kNewTabButtonHOffset + newtab_button_->WidgetWidth());
   } else {
     // Interesting corner case: if |available_width_for_tabs_| > the result
     // of the calculation in the conditional arm above, the strip is in