views: use MEDIUM for TabbedPane tabs, not NORMAL

BUG=635176

Review-Url: https://codereview.chromium.org/2315243002
Cr-Commit-Position: refs/heads/master@{#416990}

ui/views/controls/tabbed_pane/tabbed_pane.cc

@@ -275,7 +275,7 @@ void MdTab::OnStateChanged() {
       : theme->GetSystemColor(ui::NativeTheme::kColorId_ButtonEnabledColor);
   title()->SetEnabledColor(font_color);
 
-  gfx::Font::Weight font_weight = gfx::Font::Weight::NORMAL;
+  gfx::Font::Weight font_weight = gfx::Font::Weight::MEDIUM;
 #if defined(OS_WIN)
   if (selected())
     font_weight = gfx::Font::Weight::BOLD;