Add the Mojo implementation of authenticator.mojom's MakeCredential.

chrome/browser/chrome_content_browser_client.cc

Index: chrome/browser/chrome_content_browser_client.cc
diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index d032d6a83bce6a69d29c6e73ef36ec23ac4a1ef1..7434db0c37f8dd0ec9d548a0c4c5198660757c28 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -99,6 +99,7 @@
 #include "chrome/browser/ui/webui/chrome_web_ui_controller_factory.h"
 #include "chrome/browser/ui/webui/log_web_ui_url.h"
 #include "chrome/browser/usb/usb_tab_helper.h"
+#include "chrome/browser/webauth/authenticator_web_contents_manager.h"
 #include "chrome/common/channel_info.h"
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/chrome_features.h"
@@ -890,6 +891,20 @@ AppLoadedInTabSource ClassifyAppLoadedInTabSource(
 }
 #endif  // BUILDFLAG(ENABLE_EXTENSIONS)
 
+void CreateAuthenticatorForWebContents(
+    content::RenderFrameHost* render_frame_host,
+    const service_manager::BindSourceInfo& source_info,
+    webauth::mojom::AuthenticatorRequest request) {
+  content::WebContents* web_contents =
+      content::WebContents::FromRenderFrameHost(render_frame_host);
+  if (!web_contents) {
+    NOTREACHED();
+    return;

[Mike West, 2017/06/13 21:11:22]

Why `NOTREACHED()` here rather than `DCHECK(web_contents)`?

[kpaulhamus, 2017/06/15 01:27:13]

Updated.

+  }
+  AuthenticatorWebContentsManager::GetOrCreateForWebContents(web_contents)
+      ->CreateAuthenticator(render_frame_host, std::move(request));
+}
+
 void CreateUsbDeviceManager(RenderFrameHost* render_frame_host,
                             const service_manager::BindSourceInfo& source_info,
                             device::mojom::UsbDeviceManagerRequest request) {
@@ -3196,6 +3211,11 @@ void ChromeContentBrowserClient::ExposeInterfacesToFrame(
   }
 #endif
 
+  if (base::FeatureList::IsEnabled(features::kWebAuth)) {
+    registry->AddInterface(
+        base::Bind(&CreateAuthenticatorForWebContents, render_frame_host));
+  }
+
 #if defined(OS_LINUX) || defined(OS_WIN)
   if (!ChromeOriginTrialPolicy().IsFeatureDisabled("WebShare")) {
     registry->AddInterface(base::Bind(&ShareServiceImpl::Create));