Clean up NativeTheme (particularly CommonTheme).

ui/views/controls/label.cc

Index: ui/views/controls/label.cc
diff --git a/ui/views/controls/label.cc b/ui/views/controls/label.cc
index 46f86389f1503139bcf9d448ef887919c0f91ba7..0c4667dad17cab28ccb7493022d918842fb7fa85 100644
--- a/ui/views/controls/label.cc
+++ b/ui/views/controls/label.cc
@@ -596,8 +596,8 @@ void Label::UpdateColorsFromTheme(const ui::NativeTheme* theme) {
         ui::NativeTheme::kColorId_LabelDisabledColor);
   }
   if (!background_color_set_) {
-    background_color_ = theme->GetSystemColor(
-        ui::NativeTheme::kColorId_LabelBackgroundColor);
+    background_color_ =
+        theme->GetSystemColor(ui::NativeTheme::kColorId_DialogBackground);

[sky, 2016/10/03 16:12:05]

Why are you preferring dialogbackground to labelbackground? Using dialog sort of
implies labels are only used in dialogs. Maybe DialogBackground should be
WindowBackground?

[Evan Stade, 2016/10/03 19:46:44]

I'd say it only implies labels /can/ be used in dialogs, which is a fair
assumption. The label's text color has to be readable on a dialog background,
and that's what this is ensuring.
good question, I don't have a particular reason to prefer either dialog or
window, but as long as they're pretty close (and in many cases they're the same
thing) it should be ok, as this isn't actually drawn, it's just for the auto
color readability stuff.

   }
   RecalculateColors();
 }