In test code, allow any 100% data pack to provide fallbacks.

A test is allowed to request a 200% resource and fallback to a 100%
resource. Currently only the last-added 100% data pack provides
fallbacks, which may only be a small supplement.

Instead, scan through all 100% data packs. But only when
InitSharedInstanceWithPakPath() has invoked
ResourceBundle::LoadTestResources().

BUG=636995

Review-Url: https://codereview.chromium.org/2406763002
Cr-Commit-Position: refs/heads/master@{#427272}

ui/base/resource/resource_bundle.cc

@@ -822,32 +822,31 @@ bool ResourceBundle::LoadBitmap(int resource_id,
                                 SkBitmap* bitmap,
                                 bool* fell_back_to_1x) const {
   DCHECK(fell_back_to_1x);
-  ResourceHandle* data_handle_100_percent = nullptr;
-  for (size_t i = 0; i < data_packs_.size(); ++i) {
-    if (data_packs_[i]->GetScaleFactor() == ui::SCALE_FACTOR_NONE &&
-        LoadBitmap(*data_packs_[i], resource_id, bitmap, fell_back_to_1x)) {
+  for (const auto& pack : data_packs_) {
+    if (pack->GetScaleFactor() == ui::SCALE_FACTOR_NONE &&
+        LoadBitmap(*pack, resource_id, bitmap, fell_back_to_1x)) {
       DCHECK(!*fell_back_to_1x);
       *scale_factor = ui::SCALE_FACTOR_NONE;
       return true;
     }
-    if (data_packs_[i]->GetScaleFactor() == ui::SCALE_FACTOR_100P)
-      data_handle_100_percent = data_packs_[i];
 
-    if (data_packs_[i]->GetScaleFactor() == *scale_factor &&
-        LoadBitmap(*data_packs_[i], resource_id, bitmap, fell_back_to_1x)) {
+    if (pack->GetScaleFactor() == *scale_factor &&
+        LoadBitmap(*pack, resource_id, bitmap, fell_back_to_1x)) {
       return true;
     }
   }
 
   // Unit tests may only have 1x data pack. Allow them to fallback to 1x
   // resources.
-  if (*scale_factor != ui::SCALE_FACTOR_100P && is_test_resources_ &&
-      data_handle_100_percent &&
-      LoadBitmap(*data_handle_100_percent, resource_id, bitmap,
-                 fell_back_to_1x)) {
+  if (is_test_resources_ && *scale_factor != ui::SCALE_FACTOR_100P) {
+    for (const auto& pack : data_packs_) {
+      if (pack->GetScaleFactor() == ui::SCALE_FACTOR_100P &&
+          LoadBitmap(*pack, resource_id, bitmap, fell_back_to_1x)) {
         *fell_back_to_1x = true;
         return true;
       }
+    }
+  }
 
   return false;
 }

ui/base/resource/resource_bundle.h

@@ -355,7 +355,7 @@ class UI_BASE_EXPORT ResourceBundle {
   // Fills the |bitmap| given the |resource_id| and |scale_factor|.
   // Returns false if the resource does not exist. This may fall back to
   // the data pack with SCALE_FACTOR_NONE, and when this happens,
-  // |scale_factor| will be set to SCALE_FACTOR_100P.
+  // |scale_factor| will be set to SCALE_FACTOR_NONE.
   bool LoadBitmap(int resource_id,
                   ScaleFactor* scale_factor,
                   SkBitmap* bitmap,