Gtk3: Render a GtkHeaderBar as the background of the tab strip

ui/native_theme/native_theme.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_NATIVE_THEME_NATIVE_THEME_H_
 #define UI_NATIVE_THEME_NATIVE_THEME_H_
 
 #include "base/macros.h"
 #include "base/observer_list.h"
 #include "build/build_config.h"
@@ skipping 27 matching lines @@
 // ExtraParams union.  Each part that requires more information has its own
 // field in the union.
 //
 // NativeTheme also supports getting the default size of a given part with
 // the GetPartSize() method.
 class NATIVE_THEME_EXPORT NativeTheme {
  public:
   // The part to be painted / sized.
   enum Part {
     kCheckbox,
+    kFrameTopArea,
     kInnerSpinButton,
     kMenuList,
     kMenuPopupBackground,
 #if defined(OS_WIN)
     kMenuCheck,
     kMenuCheckBackground,
     kMenuPopupArrow,
     kMenuPopupGutter,
     kMenuPopupSeparator,
 #endif
@@ skipping 44 matching lines @@
   struct ButtonExtraParams {
     bool checked;
     bool indeterminate;  // Whether the button state is indeterminate.
     bool is_default;  // Whether the button is default button.
     bool is_focused;
     bool has_border;
     int classic_state;  // Used on Windows when uxtheme is not available.
     SkColor background_color;
   };
 
+  struct FrameTopAreaExtraParams {
+    // Distinguishes between active (foreground) and inactive
+    // (background) window frame styles

[Peter Kasting, 2017/01/12 22:02:56]

Nit: Trailing period.

[Tom (Use chromium acct), 2017/01/12 22:54:13]

Done.

+    bool is_active;
+    bool incognito;
+    // If the NativeTheme will paint a solid color, it should use
+    // |default_background_color|.
+    SkColor default_background_color;
+  };
+
   struct InnerSpinButtonExtraParams {
     bool spin_up;
     bool read_only;
     int classic_state;  // Used on Windows when uxtheme is not available.
   };
 
   struct MenuArrowExtraParams {
     bool pointing_right;
     // Used for the disabled state to indicate if the item is both disabled and
     // selected.
@@ skipping 78 matching lines @@
   struct TrackbarExtraParams {
     bool vertical;
     int classic_state;  // Used on Windows when uxtheme is not available.
   };
 
   union NATIVE_THEME_EXPORT ExtraParams {
     ExtraParams();
     ExtraParams(const ExtraParams& other);
 
     ButtonExtraParams button;
+    FrameTopAreaExtraParams frame_top_area;
     InnerSpinButtonExtraParams inner_spin;
     MenuArrowExtraParams menu_arrow;
     MenuCheckExtraParams menu_check;
     MenuItemExtraParams menu_item;
     MenuListExtraParams menu_list;
     MenuBackgroundExtraParams menu_background;
     ProgressBarExtraParams progress_bar;
     ScrollbarArrowExtraParams scrollbar_arrow;
     ScrollbarTrackExtraParams scrollbar_track;
     ScrollbarThumbExtraParams scrollbar_thumb;
@@ skipping 167 matching lines @@
  private:
   // Observers to notify when the native theme changes.
   base::ObserverList<NativeThemeObserver> native_theme_observers_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeTheme);
 };
 
 }  // namespace ui
 
 #endif  // UI_NATIVE_THEME_NATIVE_THEME_H_