Remove stl_util's deletion function use from content/.

content/browser/download/download_manager_impl.h

Index: content/browser/download/download_manager_impl.h
diff --git a/content/browser/download/download_manager_impl.h b/content/browser/download/download_manager_impl.h
index f9dfc8bd1ab1e39c7cb57622e0ccd0a25be56d74..e21dc123a3f764144a796856c6a88213d1e75b36 100644
--- a/content/browser/download/download_manager_impl.h
+++ b/content/browser/download/download_manager_impl.h
@@ -138,7 +138,6 @@ class CONTENT_EXPORT DownloadManagerImpl : public DownloadManager,
 
  private:
   using DownloadSet = std::set<DownloadItem*>;
-  using DownloadMap = std::unordered_map<uint32_t, DownloadItemImpl*>;
   using DownloadGuidMap = std::unordered_map<std::string, DownloadItemImpl*>;
   using DownloadItemImplVector = std::vector<DownloadItemImpl*>;
   using DownloadRemover = base::Callback<bool(const DownloadItemImpl*)>;
@@ -213,7 +212,7 @@ class CONTENT_EXPORT DownloadManagerImpl : public DownloadManager,
   // "save page as" downloads.
   // TODO(asanka): Remove this container in favor of downloads_by_guid_ as a
   // part of http://crbug.com/593020.
-  DownloadMap downloads_;
+  std::unordered_map<uint32_t, std::unique_ptr<DownloadItemImpl>> downloads_;
 
   // Same as the above, but maps from GUID to download item. Note that the
   // container is case sensitive. Hence the key needs to be normalized to