Load 2x resources on demand

 Currently, this always load 1x. This will be fixed in follow up CL to use currently used scale factor.

* Added thread check to ImageSkiaStorage using NonThreadSafe.
 This is important as GetRepresentation may change the stage
now even for the Image obtained from ResourceBundle.
* Added SetReadOnly to protect read only resources (ones in ResourceBundle) from being modified by accident.
* Addded MakeThreadSafe to guarantee that it can be safely accessed from multiple threads.

BUG=141351,144367
TEST=covered by tests. Also run with --force-device-scale-factor=2 and --load-2x-resources and make sure chrome still uses 2x resources where available.

Review URL: https://chromiumcodereview.appspot.com/10820049

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@153846 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 8 insertions, 45 deletions

diff --git a/chrome/browser/themes/browser_theme_pack.cc b/chrome/browser/themes/browser_theme_pack.cc
index a2672f7..c470ebd 100644
--- a/chrome/browser/themes/browser_theme_pack.cc
+++ b/chrome/browser/themes/browser_theme_pack.cc
@@ -436,11 +436,14 @@ scoped_refptr<BrowserThemePack> BrowserThemePack::BuildFromExtension(
   pack->CreateImages(&pack->images_on_ui_thread_);
   pack->CreateImages(&pack->images_on_file_thread_);
 
-  // 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;
-  scale_factors_in_use.push_back(ui::SCALE_FACTOR_100P);
-  pack->GenerateImageReps(scale_factors_in_use);
+  // 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->MakeThreadSafe();
+  }
 
   // The BrowserThemePack is now in a consistent state.
   return pack;
@@ -1117,14 +1120,6 @@ void BrowserThemePack::RepackImages(const ImageCache& images,
        it != images.end(); ++it) {
     gfx::ImageSkia image_skia = *it->second->ToImageSkia();
 
-    // Attempt to generate image reps for all supported scale factors.
-    for (ScaleFactors::const_iterator factor_it = scale_factors_.begin();
-         factor_it != scale_factors_.end(); ++factor_it) {
-      // Ask for representation to force the representation to be generated
-      // if it wasn't already.
-      image_skia.GetRepresentation(*factor_it);
-    }
-
     typedef std::vector<gfx::ImageSkiaRep> ImageSkiaReps;
     ImageSkiaReps image_reps = image_skia.image_reps();
     if (image_reps.empty()) {
@@ -1145,34 +1140,6 @@ void BrowserThemePack::RepackImages(const ImageCache& images,
   }
 }
 
-void BrowserThemePack::GenerateImageReps(
-    const std::vector<ui::ScaleFactor>& scale_factors) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  for (ImageCache::const_iterator it = images_on_ui_thread_.begin();
-       it != images_on_ui_thread_.end();
-       ++it) {
-    const gfx::ImageSkia* image1 = it->second->ToImageSkia();
-    const gfx::ImageSkia* image2 =
-        images_on_file_thread_[it->first]->ToImageSkia();
-
-    // Ensure that image reps are generated and cached in |image1| by
-    // calling GetRepresentation().
-    for (size_t i = 0; i < scale_factors.size(); ++i)
-      image1->GetRepresentation(scale_factors[i]);
-
-    // |image1| and |image2| have ImageSkiaSources which produce pixel
-    // equivalent output. Instead of regenerating again, copy the image reps
-    // which were generated for |image1| into |image2|.
-    // Don't do a deep copy of the SkBitmaps as SkBitmap is thread safe.
-    std::vector<gfx::ImageSkiaRep> image1_reps = image1->image_reps();
-    for (size_t i = 0; i < image1_reps.size(); ++i) {
-      gfx::ImageSkiaRep image1_rep = image1_reps[i];
-      const_cast<gfx::ImageSkia*>(image2)->AddRepresentation(gfx::ImageSkiaRep(
-          image1_rep.sk_bitmap(), image1_rep.scale_factor()));
-    }
-  }
-}
-
 void BrowserThemePack::MergeImageCaches(
     const ImageCache& source, ImageCache* destination) const {
   for (ImageCache::const_iterator it = source.begin(); it != source.end();
diff --git a/chrome/browser/themes/browser_theme_pack.h b/chrome/browser/themes/browser_theme_pack.h
index d82d44d..ea9ccc6 100644
--- a/chrome/browser/themes/browser_theme_pack.h
+++ b/chrome/browser/themes/browser_theme_pack.h
@@ -181,10 +181,6 @@ class BrowserThemePack : public base::RefCountedThreadSafe<
   void RepackImages(const ImageCache& images,
                     RawImages* reencoded_images) const;
 
-  // Generates image reps for |scale_factors| for
-  // |prepared_images_on_ui_thread_| and |prepared_images_on_file_thread_|.
-  void GenerateImageReps(const std::vector<ui::ScaleFactor>& scale_factors);
-
   // 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,