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

chrome/browser/manifest/manifest_icon_downloader.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/manifest/manifest_icon_downloader.h"
 
 #include <limits>
 
 #include "chrome/browser/manifest/manifest_icon_selector.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/web_contents.h"
 #include "skia/ext/image_operations.h"
 #include "ui/gfx/screen.h"
 
 bool ManifestIconDownloader::Download(
     content::WebContents* web_contents,
     const GURL& icon_url,
     int ideal_icon_size_in_dp,
+    int minimum_icon_size_in_dp,
     const ManifestIconDownloader::IconFetchCallback& callback) {
+  DCHECK(minimum_icon_size_in_dp <= ideal_icon_size_in_dp);
   if (!web_contents || !icon_url.is_valid())
     return false;
 
   const gfx::Screen* screen =
       gfx::Screen::GetScreenFor(web_contents->GetNativeView());
 
   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));
 
   web_contents->DownloadImage(
       icon_url,
       false, // is_favicon
       0,     // max_bitmap_size - 0 means no maximum size.
       false, // bypass_cache
       base::Bind(&ManifestIconDownloader::OnIconFetched,
                  ideal_icon_size_in_px,
                  minimum_icon_size_in_px,
                  callback));
@@ skipping 77 matching lines @@
       continue;
 
     if ((best_delta > 0 && delta < best_delta) ||
         (best_delta < 0 && delta > best_delta && delta >= max_negative_delta)) {
       best_index = i;
       best_delta = delta;
     }
   }
   return best_index;
 }