Automatically call OnNativeThemeChanged when a widget is added to a hierarchy

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 717d2e08a445b2af147a964653f10b86a80f5c81..f3175a62f250a004e0005440b999f76a2a02ab5d 100644
--- a/ui/views/controls/label.cc
+++ b/ui/views/controls/label.cc
@@ -378,14 +378,25 @@ void Label::OnPaint(gfx::Canvas* canvas) {
 }
 
 void Label::OnNativeThemeChanged(const ui::NativeTheme* theme) {
-  UpdateColorsFromTheme(theme);
+  if (!enabled_color_set_) {
+    requested_enabled_color_ = theme->GetSystemColor(
+        ui::NativeTheme::kColorId_LabelEnabledColor);
+  }
+  if (!disabled_color_set_) {
+    requested_disabled_color_ = theme->GetSystemColor(
+        ui::NativeTheme::kColorId_LabelDisabledColor);
+  }
+  if (!background_color_set_) {
+    background_color_ = theme->GetSystemColor(
+        ui::NativeTheme::kColorId_LabelBackgroundColor);
+  }
+  RecalculateColors();
 }
 
 void Label::Init(const base::string16& text, const gfx::FontList& font_list) {
   font_list_ = font_list;
   enabled_color_set_ = disabled_color_set_ = background_color_set_ = false;
   auto_color_readability_ = true;
-  UpdateColorsFromTheme(ui::NativeTheme::instance());
   horizontal_alignment_ = gfx::ALIGN_CENTER;
   line_height_ = 0;
   is_multi_line_ = false;
@@ -534,22 +545,6 @@ void Label::CalculateDrawStringParams(base::string16* paint_text,
      *flags |= gfx::Canvas::NO_ELLIPSIS;
 }
 
-void Label::UpdateColorsFromTheme(const ui::NativeTheme* theme) {
-  if (!enabled_color_set_) {
-    requested_enabled_color_ = theme->GetSystemColor(
-        ui::NativeTheme::kColorId_LabelEnabledColor);
-  }
-  if (!disabled_color_set_) {
-    requested_disabled_color_ = theme->GetSystemColor(
-        ui::NativeTheme::kColorId_LabelDisabledColor);
-  }
-  if (!background_color_set_) {
-    background_color_ = theme->GetSystemColor(
-        ui::NativeTheme::kColorId_LabelBackgroundColor);
-  }
-  RecalculateColors();
-}
-
 void Label::ResetCachedSize() {
   text_size_valid_ = false;
   cached_heights_cursor_ = 0;