Unpack theme data from extensions off of UI thread.

chrome/browser/themes/theme_service.h

Index: chrome/browser/themes/theme_service.h
diff --git a/chrome/browser/themes/theme_service.h b/chrome/browser/themes/theme_service.h
index 51c676c2d0f337cf06f18469e8f6ed485942581e..c941a63de3e10453275152fb74224563aec08c76 100644
--- a/chrome/browser/themes/theme_service.h
+++ b/chrome/browser/themes/theme_service.h
@@ -16,14 +16,17 @@
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/sequence_checker.h"
+#include "base/task/cancelable_task_tracker.h"
 #include "build/build_config.h"
 #include "chrome/common/features.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
+#include "extensions/common/extension_id.h"
 #include "extensions/features/features.h"
 #include "ui/base/theme_provider.h"
 
+class BrowserThemePack;
 class CustomThemeSupplier;
 class ThemeSyncableService;
 class Profile;
@@ -82,6 +85,9 @@ class ThemeService : public content::NotificationObserver, public KeyedService {
   // ExtensionService.
   virtual void SetTheme(const extensions::Extension* extension);
 
+  // Similar to SetTheme, but doesn't show an undo infobar.
+  void RevertToTheme(const extensions::Extension* extension);
+
   // Reset the theme to default.
   virtual void UseDefaultTheme();
 
@@ -230,6 +236,9 @@ class ThemeService : public content::NotificationObserver, public KeyedService {
   // and contrasting with the foreground tab is the most important).
   static SkColor GetSeparatorColor(SkColor tab_color, SkColor frame_color);
 
+  void DoSetTheme(const extensions::Extension* extension,
+                  bool suppress_infobar);
+
   // These methods provide the implementation for ui::ThemeProvider (exposed
   // via BrowserThemeProvider).
   gfx::ImageSkia* GetImageSkiaNamed(int id, bool incognito) const;
@@ -270,8 +279,15 @@ class ThemeService : public content::NotificationObserver, public KeyedService {
   void SaveThemeID(const std::string& id);
 
   // Implementation of SetTheme() (and the fallback from LoadThemePrefs() in
-  // case we don't have a theme pack).
-  void BuildFromExtension(const extensions::Extension* extension);
+  // case we don't have a theme pack). |new_theme| indicates whether this is a
+  // newly installed theme or a migration.
+  void BuildFromExtension(const extensions::Extension* extension,
+                          bool new_theme);
+
+  // Callback when |pack| has finished or failed building.
+  void OnThemeBuiltFromExtension(const extensions::ExtensionId& extension_id,
+                                 scoped_refptr<BrowserThemePack> pack,
+                                 bool new_theme);
 
 #if BUILDFLAG(ENABLE_SUPERVISED_USERS)
   // Returns true if the profile belongs to a supervised user.
@@ -328,6 +344,14 @@ class ThemeService : public content::NotificationObserver, public KeyedService {
 
   SEQUENCE_CHECKER(sequence_checker_);
 
+  // Allows us to cancel building a theme pack from an extension.
+  base::CancelableTaskTracker build_extension_task_tracker_;
+
+  // The ID of the theme that's currently being built on a different thread.
+  // We hold onto this just to be sure not to uninstall the extension view
+  // RemoveUnusedThemes while it's still being built.
+  std::string building_extension_id_;
+
   base::WeakPtrFactory<ThemeService> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ThemeService);