Try 2: Completely redo how themes are stored on disk and processed at install time.

chrome/browser/gtk/gtk_theme_provider.h

 // Copyright (c) 2009 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 CHROME_BROWSER_GTK_GTK_THEME_PROVIDER_H_
 #define CHROME_BROWSER_GTK_GTK_THEME_PROVIDER_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 22 matching lines @@
 
   // Calls |observer|.Observe() for the browser theme with this provider as the
   // source.
   void InitThemesFor(NotificationObserver* observer);
 
   // Overridden from BrowserThemeProvider:
   //
   // Sets that we aren't using the system theme, then calls
   // BrowserThemeProvider's implementation.
   virtual void Init(Profile* profile);
+  virtual SkBitmap* GetBitmapNamed(int id) const;
+  virtual SkColor GetColor(int id) const;
+  virtual bool HasCustomImage(int id) const;
   virtual void SetTheme(Extension* extension);
   virtual void UseDefaultTheme();
   virtual void SetNativeTheme();
 
   // Overridden from NotificationObserver:
   virtual void Observe(NotificationType type,
                        const NotificationSource& source,
                        const NotificationDetails& details);
 
   // Creates a GtkChromeButton instance, registered with this theme provider,
@@ skipping 26 matching lines @@
   // (hopefully) live on the X server, instead of the client so we don't have
   // to send the image to the server on each expose.
   CairoCachedSurface* GetSurfaceNamed(int id, GtkWidget* widget_on_display);
 
   // These functions do not add a ref to the returned pixbuf, and it should not be
   // unreffed.
   // If |native| is true, get the GTK_STOCK version of the icon.
   static GdkPixbuf* GetFolderIcon(bool native);
   static GdkPixbuf* GetDefaultFavicon(bool native);
 
- protected:
-  // Possibly creates a theme specific version of theme_toolbar_default.
-  // (minimally acceptable version right now, which is just a fill of the bg
-  // color; this should instead invoke gtk_draw_box(...) for complex theme
-  // engines.)
-  virtual SkBitmap* LoadThemeBitmap(int id) const;
+ private:
+  typedef std::map<int, SkColor> ColorMap;
+  typedef std::map<int, color_utils::HSL> TintMap;
+  typedef std::map<int, SkBitmap*> ImageCache;
 
- private:
   // Load theme data from preferences, possibly picking colors from GTK.
   virtual void LoadThemePrefs();
 
   // Let all the browser views know that themes have changed.
   virtual void NotifyThemeChanged();
 
-  // If use_gtk_ is true, completely ignores this call. Otherwise passes it to
-  // the superclass.
-  virtual void SaveThemeBitmap(const std::string resource_name, int id) const;
-
   // Additionally frees the CairoCachedSurfaces.
   virtual void FreePlatformCaches();
 
   // Handles signal from GTK that our theme has been changed.
   static void OnStyleSet(GtkWidget* widget,
                          GtkStyle* previous_style,
                          GtkThemeProvider* provider);
 
   void LoadGtkValues();
 
   // Sets the underlying theme colors/tints from a GTK color.
-  void SetThemeColorFromGtk(const char* id, GdkColor* color);
-  void SetThemeTintFromGtk(const char* id, GdkColor* color,
-                           const color_utils::HSL& default_tint);
+  void SetThemeColorFromGtk(int id, GdkColor* color);
+  void SetThemeTintFromGtk(int id, GdkColor* color);
+  void BuildTintedFrameColor(int color_id, int tint_id);
+  void SetTintToExactColor(int id, GdkColor* color);
 
   // Split out from FreePlatformCaches so it can be called in our destructor;
   // FreePlatformCaches() is called from the BrowserThemeProvider's destructor,
   // but by the time ~BrowserThemeProvider() is run, the vtable no longer
   // points to GtkThemeProvider's version.
   void FreePerDisplaySurfaces();
 
+  // Lazily generates each bitmap used in the gtk theme.
+  SkBitmap* GenerateGtkThemeBitmap(int id) const;
+
+  // Tints IDR_THEME_FRAME based based on |tint_id|. Used during lazy
+  // generation of the gtk theme bitmaps.
+  SkBitmap* GenerateFrameImage(int tint_id) const;
+
+  // Takes the base frame image |base_id| and tints it with |tint_id|.
+  SkBitmap* GenerateTabImage(int base_id) const;
+
   // A notification from the GtkChromeButton GObject destructor that we should
   // remove it from our internal list.
   static void OnDestroyChromeButton(GtkWidget* button,
                                     GtkThemeProvider* provider);
 
   // Whether we should be using gtk rendering.
   bool use_gtk_;
 
   // GtkWidgets that exist only so we can look at their properties (and take
   // their colors).
   GtkWidget* fake_window_;
   OwnedWidgetGtk fake_label_;
 
   // A list of all GtkChromeButton instances. We hold on to these to notify
   // them of theme changes.
   std::vector<GtkWidget*> chrome_buttons_;
 
+  // Tints and colors calculated by LoadGtkValues() that are given to the
+  // caller while |use_gtk_| is true.
+  ColorMap colors_;
+  TintMap tints_;
+
+  // Image cache of lazily created images, created when requested by
+  // GetBitmapNamed().
+  mutable ImageCache gtk_images_;
+
   // Cairo surfaces for each GdkDisplay.
   typedef std::map<int, CairoCachedSurface*> CairoCachedSurfaceMap;
   typedef std::map<GdkDisplay*, CairoCachedSurfaceMap> PerDisplaySurfaceMap;
   PerDisplaySurfaceMap per_display_surfaces_;
 
   // This is a dummy widget that only exists so we have something to pass to
   // gtk_widget_render_icon().
   static GtkWidget* icon_widget_;
 
   // The default folder icon and default bookmark icon for the GTK theme.
   // These are static because the system can only have one theme at a time.
   // They are cached when they are requested the first time, and cleared when
   // the system theme changes.
   static GdkPixbuf* default_folder_icon_;
   static GdkPixbuf* default_bookmark_icon_;
 };
 
 #endif  // CHROME_BROWSER_GTK_GTK_THEME_PROVIDER_H_