Remove some unused theming code for GTK.

ui/views/linux_ui/linux_ui.h

 // Copyright 2013 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_VIEWS_LINUX_UI_LINUX_UI_H_
 #define UI_VIEWS_LINUX_UI_LINUX_UI_H_
 
 #include <string>
 
 #include "base/callback.h"
@@ skipping 66 matching lines @@
   //
   // Can return NULL, in case no toolkit has been set. (For example, if we're
   // running with the "--ash" flag.)
   static LinuxUI* instance();
 
   virtual void Initialize() = 0;
   // TODO(varkha): This should not be necessary once Material Design is on
   // unconditionally.
   virtual void MaterialDesignControllerReady() = 0;
 
-  // Returns a themed image per theme_provider.h
-  virtual gfx::Image GetThemeImageNamed(int id) const = 0;
   virtual bool GetTint(int id, color_utils::HSL* tint) const = 0;
   virtual bool GetColor(int id, SkColor* color) const = 0;
-  virtual bool HasCustomImage(int id) const = 0;
 
   // Returns the preferences that we pass to WebKit.
   virtual SkColor GetFocusRingColor() const = 0;
   virtual SkColor GetThumbActiveColor() const = 0;
   virtual SkColor GetThumbInactiveColor() const = 0;
   virtual SkColor GetTrackColor() const = 0;
   virtual SkColor GetActiveSelectionBgColor() const = 0;
   virtual SkColor GetActiveSelectionFgColor() const = 0;
   virtual SkColor GetInactiveSelectionBgColor() const = 0;
   virtual SkColor GetInactiveSelectionFgColor() const = 0;
@@ skipping 61 matching lines @@
   // recalculated.
   virtual void UpdateDeviceScaleFactor(float device_scale_factor) = 0;
 
   // Determines the device scale factor of the primary screen.
   virtual float GetDeviceScaleFactor() const = 0;
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_LINUX_UI_LINUX_UI_H_