Add browser test for CustomizationWallpaperDownloader.

chrome/browser/chromeos/customization_wallpaper_downloader.cc

Index: chrome/browser/chromeos/customization_wallpaper_downloader.cc
diff --git a/chrome/browser/chromeos/customization_wallpaper_downloader.cc b/chrome/browser/chromeos/customization_wallpaper_downloader.cc
index d672945a980ec125c459404408148e79889ae701..674474ebd21147208cc7971c6179ebd717c2f959 100644
--- a/chrome/browser/chromeos/customization_wallpaper_downloader.cc
+++ b/chrome/browser/chromeos/customization_wallpaper_downloader.cc
@@ -72,6 +72,7 @@ CustomizationWallpaperDownloader::CustomizationWallpaperDownloader(
       wallpaper_temporary_file_(wallpaper_downloaded_file.value() +
                                 kTemporarySuffix),
       retries_(0),
+      retry_delay_(base::TimeDelta::FromSeconds(kRetrySleepSeconds)),
       on_wallpaper_fetch_completed_(on_wallpaper_fetch_completed),
       weak_factory_(this) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
@@ -105,9 +106,9 @@ void CustomizationWallpaperDownloader::Retry() {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   ++retries_;
 
-  const double delay_seconds =
-      std::min(kMaxRetrySleepSeconds,
-               static_cast<double>(retries_) * retries_ * kRetrySleepSeconds);
+  const double delay_seconds = std::min(
+      kMaxRetrySleepSeconds,
+      static_cast<double>(retries_) * retries_ * retry_delay_.InSecondsF());
   const base::TimeDelta delay =
       base::TimeDelta::FromSeconds(lround(delay_seconds));