Implement basic mojo Permission service and use it for Geolocation.

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 a5891146486b4618991cd2593c788072d41ab9b2..e96f3a2a07d6060facb44ae3b3f42bdf62382058 100644
--- a/content/browser/frame_host/render_frame_host_impl.cc
+++ b/content/browser/frame_host/render_frame_host_impl.cc
@@ -25,6 +25,8 @@
 #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/geolocation/geolocation_service_context.h"
+#include "content/browser/permissions/permission_service_context.h"
+#include "content/browser/permissions/permission_service_impl.h"
 #include "content/browser/renderer_host/input/input_router.h"
 #include "content/browser/renderer_host/input/timeout_monitor.h"
 #include "content/browser/renderer_host/render_process_host_impl.h"
@@ -1267,6 +1269,12 @@ void RenderFrameHostImpl::RegisterMojoServices() {
                    base::Bind(&RenderFrameHostImpl::DidUseGeolocationPermission,
                               base::Unretained(this))));
   }
+
+  scoped_ptr<PermissionServiceContext> permission_service_context(
+      new PermissionServiceContext(this));
+  GetServiceRegistry()->AddService(
+      base::Bind(&PermissionServiceImpl::Create,
+                 base::Passed(&permission_service_context)));

[qsr, 2014/11/14 09:20:26]

This callback will be run each time something connect to the permission service.
Given that the first call will pass the context to the first instance, all other
instance will have a null context.

[mlamouri (slow - plz ping), 2014/11/14 11:37:11]

I might need some deeper understanding on how things work. My understanding was
that there would be one service per RFH. Do you mean that there is one service
instance per clients? Maybe in our case it doesn't change much because there is
a 1:1 relationship betweer RF/RFH?

[qsr, 2014/11/14 11:49:27]

 What you register is a factory. Each time something will request a connection
to the service, the factory will be called. So you need to consider that it will
be called more than once. That's why you should share the context between all
the instances. What Collin was suggesting (and I agree) is to have the context
owned by the RFH. It can then have the factory method itself, and each time it
creates a service, it owns it (using WeakBind instead of Bind), and delete all
of those when it is killed. It should also monitor the service for connection
error and delete those that go into an error state.

 }
 
 void RenderFrameHostImpl::SetState(RenderFrameHostImplState rfh_state) {