webapps: allow callers of icon downloader/selector to specify a minimum size

chrome/browser/manifest/manifest_icon_selector.cc

Index: chrome/browser/manifest/manifest_icon_selector.cc
diff --git a/chrome/browser/manifest/manifest_icon_selector.cc b/chrome/browser/manifest/manifest_icon_selector.cc
index 5d9cb593e57520e32b7aa97adbdacf67247ad1fe..21e0d460d2f585cb3919b7cd7aaa626c8a9e22aa 100644
--- a/chrome/browser/manifest/manifest_icon_selector.cc
+++ b/chrome/browser/manifest/manifest_icon_selector.cc
@@ -164,15 +164,16 @@ std::vector<Manifest::Icon> ManifestIconSelector::FilterIconsByType(
 GURL ManifestIconSelector::FindBestMatchingIcon(
     const std::vector<Manifest::Icon>& unfiltered_icons,
     const int ideal_icon_size_in_dp,
+    const int minimum_icon_size_in_dp,
     const gfx::Screen* screen) {
+  DCHECK(minimum_icon_size_in_dp <= ideal_icon_size_in_dp);
+
   const float device_scale_factor =
       screen->GetPrimaryDisplay().device_scale_factor();
   const int ideal_icon_size_in_px =
       static_cast<int>(round(ideal_icon_size_in_dp * device_scale_factor));
-
-  const float minimum_scale_factor = std::max(device_scale_factor - 1, 1.0f);
   const int minimum_icon_size_in_px =
-      static_cast<int>(round(ideal_icon_size_in_dp * minimum_scale_factor));
+      static_cast<int>(round(minimum_icon_size_in_dp * device_scale_factor));
 
   std::vector<Manifest::Icon> icons =
       ManifestIconSelector::FilterIconsByType(unfiltered_icons);