Unpack theme data from extensions off of UI thread.

chrome/browser/themes/browser_theme_pack.h

Index: chrome/browser/themes/browser_theme_pack.h
diff --git a/chrome/browser/themes/browser_theme_pack.h b/chrome/browser/themes/browser_theme_pack.h
index cc975cc1ce193ac82335a12617ad942aebb6f1dd..d527e97342d83390848ffa9430e6763c5736596c 100644
--- a/chrome/browser/themes/browser_theme_pack.h
+++ b/chrome/browser/themes/browser_theme_pack.h
@@ -53,11 +53,11 @@ class DataPack;
 // will trip our IO on the UI thread detector.
 class BrowserThemePack : public CustomThemeSupplier {
  public:
-  // Builds the theme pack from all data from |extension|. This is often done
-  // on a separate thread as it takes so long. This can fail and return NULL in
-  // the case where the theme has invalid data.
-  static scoped_refptr<BrowserThemePack> BuildFromExtension(
-      const extensions::Extension* extension);
+  // Builds the theme from |extension| into |pack|. This may be done on a
+  // separate thread as it takes so long. This can fail in the case where the
+  // theme has invalid data, in which case |pack->is_valid()| will be false.
+  static void BuildFromExtension(const extensions::Extension* extension,
+                                 scoped_refptr<BrowserThemePack> pack);
 
   // Builds the theme pack from a previously performed WriteToDisk(). This
   // operation should be relatively fast, as it should be an mmap() and some
@@ -69,6 +69,11 @@ class BrowserThemePack : public CustomThemeSupplier {
   // in the data pack.
   static bool IsPersistentImageID(int id);
 
+  // Default. Everything is empty.
+  BrowserThemePack();
+
+  bool is_valid() const { return is_valid_; }
+
   // 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
@@ -103,9 +108,6 @@ class BrowserThemePack : public CustomThemeSupplier {
   // Maps image ids to maps of scale factors to file paths.
   typedef std::map<int, ScaleFactorToFileMap> FilePathMap;
 
-  // Default. Everything is empty.
-  BrowserThemePack();
-
   ~BrowserThemePack() override;
 
   // Builds a header ready to write to disk.
@@ -217,7 +219,7 @@ class BrowserThemePack : public CustomThemeSupplier {
 
     // theme_id without NULL terminator.
     uint8_t theme_id[16];
-  } *header_;
+  }* header_ = nullptr;
 
   // The remaining structs represent individual entries in an array. For the
   // following three structs, BrowserThemePack will either allocate an array or
@@ -227,21 +229,21 @@ class BrowserThemePack : public CustomThemeSupplier {
     double h;
     double s;
     double l;
-  } *tints_;
+  }* tints_ = nullptr;
 
   struct ColorPair {
     int32_t id;
     SkColor color;
-  } *colors_;
+  }* colors_ = nullptr;
 
   struct DisplayPropertyPair {
     int32_t id;
     int32_t property;
-  } *display_properties_;
+  }* display_properties_ = nullptr;
 
   // A list of included source images. A pointer to a -1 terminated array of
   // our persistent IDs.
-  int* source_images_;
+  int* source_images_ = nullptr;
 #pragma pack(pop)
 
   // The scale factors represented by the images in the theme pack.
@@ -254,9 +256,8 @@ class BrowserThemePack : public CustomThemeSupplier {
   RawImages image_memory_;
 
   // Loaded images. These are loaded from |image_memory_|, from |data_pack_|,
-  // and by BuildFromExtension(). These images should only be accessed on the UI
-  // thread.
-  ImageCache images_on_ui_thread_;
+  // and by BuildFromExtension().
+  ImageCache images_;
 
   // Cache of images created in BuildFromExtension(). Once the theme pack is
   // created, this cache should only be accessed on the file thread. There
@@ -264,6 +265,10 @@ class BrowserThemePack : public CustomThemeSupplier {
   // or vice versa.
   ImageCache images_on_file_thread_;
 
+  // Whether the theme pack has been succesfully initialized and is ready to
+  // use.
+  bool is_valid_ = false;
+
   DISALLOW_COPY_AND_ASSIGN(BrowserThemePack);
 };