initial version of the headless download manager delegate

headless/lib/browser/headless_browser_context_impl.h

Index: headless/lib/browser/headless_browser_context_impl.h
diff --git a/headless/lib/browser/headless_browser_context_impl.h b/headless/lib/browser/headless_browser_context_impl.h
index e6a77f107c897a461fd13243aca87cdb89190c5e..85a2ae298fd227bdb36aec80f1ba72a62fcb5389 100644
--- a/headless/lib/browser/headless_browser_context_impl.h
+++ b/headless/lib/browser/headless_browser_context_impl.h
@@ -21,6 +21,7 @@
 
 namespace headless {
 class HeadlessBrowserImpl;
+class HeadlessDownloadManagerDelegate;
 class HeadlessResourceContext;
 class HeadlessWebContentsImpl;
 
@@ -103,6 +104,7 @@ class HeadlessBrowserContextImpl : public HeadlessBrowserContext,
   HeadlessBrowserImpl* browser_;  // Not owned.
   std::unique_ptr<HeadlessBrowserContextOptions> context_options_;
   std::unique_ptr<HeadlessResourceContext> resource_context_;
+  std::unique_ptr<HeadlessDownloadManagerDelegate> download_manager_delegate_;
   base::FilePath path_;
 
   std::unordered_map<std::string, std::unique_ptr<HeadlessWebContents>>