Load 2x resources on demand

chrome/browser/themes/browser_theme_pack.cc

Index: chrome/browser/themes/browser_theme_pack.cc
diff --git a/chrome/browser/themes/browser_theme_pack.cc b/chrome/browser/themes/browser_theme_pack.cc
index a2672f77520aea90eed1443e661b2c4e71f8448e..d9ea23171a6418fa7e56d0881331c0dbdc1c60ab 100644
--- a/chrome/browser/themes/browser_theme_pack.cc
+++ b/chrome/browser/themes/browser_theme_pack.cc
@@ -436,6 +436,16 @@ scoped_refptr<BrowserThemePack> BrowserThemePack::BuildFromExtension(
   pack->CreateImages(&pack->images_on_ui_thread_);
   pack->CreateImages(&pack->images_on_file_thread_);
 
+  // Make sure the images_on_file_thread_ has bitmaps for supported
+  // scale factors before passing to FILE thread.
+  for (ImageCache::iterator it = pack->images_on_file_thread_.begin();
+       it != pack->images_on_file_thread_.end(); ++it) {
+    gfx::ImageSkia* image_skia =
+        const_cast<gfx::ImageSkia*>(it->second->ToImageSkia());
+    image_skia->EnsureRepsForSupportedScaleFactors();
+    image_skia->DeleteSource();
+  }

[pkotwicz, 2012/08/23 16:58:48]

Why don't you make images_on_ui_thread_ have images for all supported scale
factors and then do a copy to images_on_file_thread_?
Also you don't need the code below: pack->GenerateImageReps() anymore.

[oshima, 2012/08/23 17:16:50]

Because images in UI thread only needs scales that are in use.
It'd be waste of memory to load them all. That's why I was asking if we can
release images_on_file_thread_ after it's written.
Ah, you're right. Thank you for the catch! Done.

+
   // For M22, as it is not possible to easily determine which scale factors are
   // in use, assume that the 1x scale factor is in use.
   std::vector<ui::ScaleFactor> scale_factors_in_use;