add print to pdf for headless

headless/lib/browser/headless_web_contents_impl.cc

Index: headless/lib/browser/headless_web_contents_impl.cc
diff --git a/headless/lib/browser/headless_web_contents_impl.cc b/headless/lib/browser/headless_web_contents_impl.cc
index 42db63f54b4a54db9ff9f3a30e7866ca076fc92d..e1f0bbe7cd1e1a70ec58829d42ecb297a1f6de67 100644
--- a/headless/lib/browser/headless_web_contents_impl.cc
+++ b/headless/lib/browser/headless_web_contents_impl.cc
@@ -30,6 +30,7 @@
 #include "headless/lib/browser/headless_browser_impl.h"
 #include "headless/lib/browser/headless_browser_main_parts.h"
 #include "headless/lib/browser/headless_devtools_client_impl.h"
+#include "headless/lib/browser/headless_print_manager.h"
 #include "services/service_manager/public/cpp/interface_registry.h"
 
 namespace headless {
@@ -172,6 +173,7 @@ HeadlessWebContentsImpl::HeadlessWebContentsImpl(
       agent_host_(content::DevToolsAgentHost::GetOrCreateFor(web_contents)),
       browser_context_(browser_context),
       render_process_host_(web_contents->GetRenderProcessHost()) {
+  printing::HeadlessPrintManager::CreateForWebContents(web_contents);
   web_contents_->SetDelegate(web_contents_delegate_.get());
   render_process_host_->AddObserver(this);
 }