getInstalledRelatedApps: Add browser-side Mojo service (stub).

content/browser/frame_host/render_frame_host_impl.cc

Index: content/browser/frame_host/render_frame_host_impl.cc
diff --git a/content/browser/frame_host/render_frame_host_impl.cc b/content/browser/frame_host/render_frame_host_impl.cc
index e6eb050896fbef0b0b43002ca613443e912bf69d..b902eea62077e0a208bf3482e9bd2bade2c441f7 100644
--- a/content/browser/frame_host/render_frame_host_impl.cc
+++ b/content/browser/frame_host/render_frame_host_impl.cc
@@ -37,6 +37,7 @@
 #include "content/browser/frame_host/render_frame_host_delegate.h"
 #include "content/browser/frame_host/render_frame_proxy_host.h"
 #include "content/browser/frame_host/render_widget_host_view_child_frame.h"
+#include "content/browser/installedapp/installed_app_provider_impl_default.h"
 #include "content/browser/loader/resource_dispatcher_host_impl.h"
 #include "content/browser/media/media_interface_proxy.h"
 #include "content/browser/media/session/media_session_service_impl.h"
@@ -2307,6 +2308,12 @@ void RenderFrameHostImpl::OnShowCreatedWindow(int pending_widget_routing_id,
 void RenderFrameHostImpl::RegisterMojoInterfaces() {
   device::GeolocationServiceContext* geolocation_service_context =
       delegate_ ? delegate_->GetGeolocationServiceContext() : NULL;
+  // The default (no-op) implementation of InstalledAppProvider.
+  // TODO(mgiuca): Implement the "real" one for Android in Java, and do not add
+  // the default one on that platform.
+  GetInterfaceRegistry()->AddInterface(

[clamy, 2017/02/27 14:49:27]

Do we envision the InstalledAppProvider to be used on desktop or will it only be
used on Android? If the later, does it make sense to register an interface
that's doing nothing on desktop? Why not register it just on Android?

[Matt Giuca, 2017/02/27 22:51:15]

We might do it on desktop in the future but no immediate plans (and it isn't
clear what that would mean).

We still want it to work on desktop, and simply return the empty list. I think
that is the best answer to "what native apps are installed?" on a platform that
doesn't have a concept of related native apps. (The web platform team does not
want APIs to be undefined on one platform or another if possible.)

If there was no Mojo service, then we would just fail to get a connection and it
would never resolve the promise. The alternative, I guess, would be to
platform-detect in the Blink code and only try to call the Mojo service on
Android. But I think it's cleaner to have Blink be unaware of the platform, and
have the Chrome-side implementation diverge by registering different Mojo
services.

[clamy, 2017/03/02 13:31:53]

Acknowledged.

+      base::Bind(&InstalledAppProviderImplDefault::Create));
+
   if (geolocation_service_context) {
     // TODO(creis): Bind process ID here so that GeolocationServiceImpl
     // can perform permissions checks once site isolation is complete.