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

chrome/browser/browser_theme_pack.h

Index: chrome/browser/browser_theme_pack.h
diff --git a/chrome/browser/browser_theme_pack.h b/chrome/browser/browser_theme_pack.h
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+// 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_BROWSER_THEME_PACK_H_
+#define CHROME_BROWSER_BROWSER_THEME_PACK_H_
+
+#include <map>
+#include <string>
+
+#include "app/gfx/color_utils.h"
+#include "base/basictypes.h"
+#include "base/scoped_ptr.h"
+#include "base/ref_counted.h"
+#include "chrome/common/extensions/extension.h"
+
+class BrowserThemeProviderTest;
+namespace base {
+class DataPack;
+}
+class DictionaryValue;
+class FilePath;
+class RefCountedMemory;
+
+// An optimized representation of a theme, backed by a mmapped DataPack.
+//
+// The idea is to pre-process all images (tinting, compositing, etc) at theme
+// install time, save all the PNG-ified data into an mmappable file so we don't
+// suffer multiple file system access times, therefore solving two of the
+// problems with the previous implementation.
+//
+// A note on const-ness. All public, non-static methods are const.  We do this
+// because once we've constructed a BrowserThemePack through the
+// BuildFromExtension() interface, we WriteToDisk() on a thread other than the
+// UI thread that consumes a BrowserThemePack.
+class BrowserThemePack : public base::RefCountedThreadSafe<BrowserThemePack> {
+ public:
+  ~BrowserThemePack();
+
+  // Builds the theme pack from all data from |extension|. This is often done
+  // on a separate thread as it takes so long.
+  static BrowserThemePack* BuildFromExtension(Extension* extension);
+
+  // Builds the theme pack from a previously WriteToDisk(). This operation

[Miranda Callahan, 2009/12/14 20:47:51]

"from a previous WriteToDisk() operation", or "from a previously performed
WriteToDisk()"

+  // should be relatively fast, as it should be an mmap() and some pointer
+  // swizzling. Returns NULL on any error attempting to read |path|.
+  static scoped_refptr<BrowserThemePack> BuildFromDataPack(
+      FilePath path, const std::string& expected_id);
+
+  // Builds a data pack on disk at |path| for future quick loading by
+  // BuildFromDataPack(). Often (but not always) called from the file thread;
+  // implementation should be threadsafe because neither thread will write to
+  // |image_memory_| and the worker thread will keep a reference to prevent
+  // destruction.
+  bool WriteToDisk(FilePath path) const;
+
+  // Returns data from the pack, or the default value if |id| doesn't
+  // exist. These methods should only be called from the UI thread. (But this
+  // isn't enforced because of unit tests).
+  bool GetTint(int id, color_utils::HSL* hsl) const;
+  bool GetColor(int id, SkColor* color) const;
+  bool GetDisplayProperty(int id, int* result) const;
+  SkBitmap* GetBitmapNamed(int id) const;
+  RefCountedMemory* GetRawData(int id) const;
+
+  // Whether this theme provides an image for |id|.
+  bool HasCustomImage(int id) const;
+
+ private:
+  friend class BrowserThemePackTest;
+
+  // Cached images. We cache all retrieved and generated bitmaps and keep
+  // track of the pointers. We own these and will delete them when we're done
+  // using them.
+  typedef std::map<int, SkBitmap*> ImageCache;
+
+  // The raw PNG memory associated with a certain id.
+  typedef std::map<int, scoped_refptr<RefCountedMemory> > RawImages;
+
+  // Default. Everything is empty.
+  BrowserThemePack();
+
+  // Builds a header ready to write to disk.
+  void BuildHeader(Extension* extension);
+
+  // Transforms the JSON tint values into their final versions in the |tints_|
+  // array.
+  void BuildTintsFromJSON(DictionaryValue* tints_value);
+
+  // Transforms the JSON color values into their final versions in the
+  // |colors_| array and also fills in unspecified colors based on tint values.
+  void BuildColorsFromJSON(DictionaryValue* color_value);
+
+  // Implementation details of BuildColorsFromJSON().
+  void ReadColorsFromJSON(DictionaryValue* colors_value,
+                          std::map<int, SkColor>* temp_colors);
+  void GenerateMissingColors(std::map<int, SkColor>* temp_colors);
+
+  // Transforms the JSON display properties into |display_properties_|.
+  void BuildDisplayPropertiesFromJSON(DictionaryValue* display_value);
+
+  // Parses the image names out of an extension.
+  void ParseImageNamesFromJSON(DictionaryValue* images_value,
+                               FilePath images_path,
+                               std::map<int, FilePath>* file_paths) const;
+
+  // Loads the unmodified bitmaps packed in the extension to SkBitmaps.
+  void LoadRawBitmapsTo(const std::map<int, FilePath>& file_paths,
+                        ImageCache* raw_bitmaps);
+
+  // Creates tinted and composited frame images. Source and destination is
+  // |bitmaps|.
+  void GenerateFrameImages(ImageCache* bitmaps) const;
+
+  // Generates button images tinted with |button_tint| and places them in
+  // processed_bitmaps.
+  void GenerateTintedButtons(color_utils::HSL button_tint,
+                             ImageCache* processed_bitmaps) const;
+
+  // Generates the semi-transparent tab background images, putting the results
+  // in |bitmaps|. Must be called after GenerateFrameImages().
+  void GenerateTabBackgroundImages(ImageCache* bitmaps) const;
+
+  // Takes all the SkBitmaps in |image_cache_|, encodes them as PNGs and places
+  // them in |image_memory_|.
+  void RepackImageCacheToImageMemory();
+
+  // Takes all images in |source| and puts them in |destination|, freeing any
+  // image already in |destination| that |source| would overwrite.
+  void MergeImageCaches(const ImageCache& source,
+                        ImageCache* destination) const;
+
+  // Retrieves the tint OR the default tint. Unlike the public interface, we
+  // always need to return a reasonable tint here, instead of partially
+  // querying if the tint exists.
+  color_utils::HSL GetTintInternal(int id) const;
+
+  // Data pack, if we have one.
+  scoped_ptr<base::DataPack> data_pack_;
+
+  // All structs written to disk need to be packed; no alignment tricks here,
+  // please.
+#pragma pack(push,1)
+  // Header that is written to disk.
+  struct BrowserThemePackHeader {
+    // Numeric version to make sure we're compatible in the future.
+    int32 version;
+
+    // 1 if little_endian. 0 if big_endian. On mismatch, abort load.
+    int32 little_endian;
+
+    // theme_id without NULL terminator.
+    uint8 theme_id[16];
+  } *header_;
+
+  // The remaining structs represent individual entries in an array. For the
+  // following three structs, BrowserThemePack will either allocate an array or
+  // will point directly to mmapped data.
+  struct TintEntry {
+    int32 id;
+    double h;
+    double s;
+    double l;
+  } *tints_;
+
+  struct ColorPair {
+    int32 id;
+    SkColor color;
+  } *colors_;
+
+  struct DisplayPropertyPair {
+    int32 id;
+    int32 property;
+  } *display_properties_;
+#pragma pack(pop)
+
+  // References to raw PNG data. This map isn't touched when |data_pack_| is
+  // non-NULL; |image_memory_| is only filled during BuildFromExtension(). Any
+  // image data that needs to be written to the DataPack during WriteToDisk()
+  // needs to be in |image_memory_|.
+  RawImages image_memory_;
+
+  // Tinted (or otherwise prepared) images for passing out. BrowserThemePack
+  // owns all these images. This cache isn't touched when we write our data to
+  // a DataPack.
+  mutable ImageCache image_cache_;
+
+  DISALLOW_COPY_AND_ASSIGN(BrowserThemePack);
+};
+
+#endif  // CHROME_BROWSER_BROWSER_THEME_PACK_H_