Use the maximum device scale factor to determine the resolution of thumbnails.

This CL introduces GetMaxScaleFactor in layout.h and uses it for determining the 
resolution of thumbnails. 

Original CL: http://codereview.chromium.org/11264025/
This CL is slightly modified to sort the supported scale factors.

BUG=155065
TEST=updated LayoutTest

Review URL: https://chromiumcodereview.appspot.com/11367064

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@165797 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 40 insertions, 4 deletions

diff --git a/ui/base/resource/resource_bundle.cc b/ui/base/resource/resource_bundle.cc
index db6cb55..420330a 100644
--- a/ui/base/resource/resource_bundle.cc
+++ b/ui/base/resource/resource_bundle.cc
@@ -34,6 +34,10 @@
 #include "ui/gfx/size_conversions.h"
 #include "ui/gfx/skbitmap_operations.h"
 
+#if defined(OS_CHROMEOS)
+#include "base/chromeos/chromeos_version.h"
+#endif
+
 namespace ui {
 
 namespace {
@@ -229,7 +233,7 @@ void ResourceBundle::AddDataPackFromFile(base::PlatformFile file,
   scoped_ptr<DataPack> data_pack(
       new DataPack(scale_factor));
   if (data_pack->LoadFromFile(file)) {
-    data_packs_.push_back(data_pack.release());
+    AddDataPack(data_pack.release());
   } else {
     LOG(ERROR) << "Failed to load data pack from file."
                << "\nSome features may not be available.";
@@ -306,7 +310,7 @@ void ResourceBundle::LoadTestResources(const FilePath& path,
   scoped_ptr<DataPack> data_pack(
       new DataPack(SCALE_FACTOR_100P));
   if (!path.empty() && data_pack->LoadFromPath(path))
-    data_packs_.push_back(data_pack.release());
+    AddDataPack(data_pack.release());
 
   data_pack.reset(new DataPack(ui::SCALE_FACTOR_NONE));
   if (!locale_path.empty() && data_pack->LoadFromPath(locale_path)) {
@@ -518,7 +522,8 @@ void ResourceBundle::ReloadFonts() {
 ResourceBundle::ResourceBundle(Delegate* delegate)
     : delegate_(delegate),
       images_and_fonts_lock_(new base::Lock),
-      locale_resources_data_lock_(new base::Lock) {
+      locale_resources_data_lock_(new base::Lock),
+      max_scale_factor_(SCALE_FACTOR_100P) {
 }
 
 ResourceBundle::~ResourceBundle() {
@@ -548,13 +553,30 @@ void ResourceBundle::AddDataPackFromPathInternal(const FilePath& path,
   scoped_ptr<DataPack> data_pack(
       new DataPack(scale_factor));
   if (data_pack->LoadFromPath(pack_path)) {
-    data_packs_.push_back(data_pack.release());
+    AddDataPack(data_pack.release());
   } else if (!optional) {
     LOG(ERROR) << "Failed to load " << pack_path.value()
                << "\nSome features may not be available.";
   }
 }
 
+void ResourceBundle::AddDataPack(DataPack* data_pack) {
+  data_packs_.push_back(data_pack);
+
+#if defined(OS_CHROMEOS)
+  // When Chrome is running on desktop and force-device-scale-factor is not
+  // specified, use SCALE_FACTOR_100P as |max_scale_factor_|.
+  if (!base::chromeos::IsRunningOnChromeOS() &&
+      !CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kForceDeviceScaleFactor))
+    return;
+#endif
+
+  if (GetScaleFactorScale(data_pack->GetScaleFactor()) >
+      GetScaleFactorScale(max_scale_factor_))
+    max_scale_factor_ = data_pack->GetScaleFactor();
+}
+
 void ResourceBundle::LoadFontsIfNecessary() {
   images_and_fonts_lock_->AssertAcquired();
   if (!base_font_.get()) {
diff --git a/ui/base/resource/resource_bundle.h b/ui/base/resource/resource_bundle.h
index 49657a1..b5424de 100644
--- a/ui/base/resource/resource_bundle.h
+++ b/ui/base/resource/resource_bundle.h
@@ -33,6 +33,7 @@ class RefCountedStaticMemory;
 
 namespace ui {
 
+class DataPack;
 class ResourceHandle;
 
 // ResourceBundle is a central facility to load images and other resources,
@@ -246,6 +247,12 @@ class UI_EXPORT ResourceBundle {
   FilePath GetLocaleFilePath(const std::string& app_locale,
                              bool test_file_exists);
 
+  // Returns the maximum scale factor currently loaded.
+  // Returns SCALE_FACTOR_100P if no resource is loaded.
+  ScaleFactor max_scale_factor() const {
+    return max_scale_factor_;
+  }
+
  private:
   FRIEND_TEST_ALL_PREFIXES(ResourceBundle, DelegateGetPathForResourcePack);
   FRIEND_TEST_ALL_PREFIXES(ResourceBundle, DelegateGetPathForLocalePack);
@@ -279,6 +286,10 @@ class UI_EXPORT ResourceBundle {
                                    ScaleFactor scale_factor,
                                    bool optional);
 
+  // Inserts |data_pack| to |data_pack_| and updates |max_scale_factor_|
+  // accordingly.
+  void AddDataPack(DataPack* data_pack);
+
   // Try to load the locale specific strings from an external data module.
   // Returns the locale that is loaded.
   std::string LoadLocaleResources(const std::string& pref_locale);
@@ -331,6 +342,9 @@ class UI_EXPORT ResourceBundle {
   scoped_ptr<ResourceHandle> locale_resources_data_;
   ScopedVector<ResourceHandle> data_packs_;
 
+  // The maximum scale factor currently loaded.
+  ScaleFactor max_scale_factor_;
+
   // Cached images. The ResourceBundle caches all retrieved images and keeps
   // ownership of the pointers.
   typedef std::map<int, gfx::Image> ImageMap;