mus: Introduce AcceleratorRegistrar and AcceleratorHandler.

mash/wm/window_manager_application.cc

Index: mash/wm/window_manager_application.cc
diff --git a/mash/wm/window_manager_application.cc b/mash/wm/window_manager_application.cc
index 1e934c6699654233331f22d35dc5ddc2f27ed10b..1cf17e308ef46d55a12a6e2b876f5df22370c0cc 100644
--- a/mash/wm/window_manager_application.cc
+++ b/mash/wm/window_manager_application.cc
@@ -4,11 +4,13 @@
 
 #include "mash/wm/window_manager_application.h"
 
+#include "base/bind.h"
 #include "components/mus/common/util.h"
 #include "components/mus/public/cpp/event_matcher.h"
 #include "components/mus/public/cpp/window.h"
 #include "components/mus/public/cpp/window_tree_connection.h"
 #include "components/mus/public/cpp/window_tree_host_factory.h"
+#include "mash/wm/accelerator_registrar_impl.h"
 #include "mash/wm/background_layout.h"
 #include "mash/wm/shelf_layout.h"
 #include "mash/wm/window_layout.h"
@@ -51,6 +53,11 @@ void WindowManagerApplication::AddAccelerators() {
                             mus::mojom::EVENT_FLAGS_CONTROL_DOWN));
 }
 
+void WindowManagerApplication::OnAcceleratorRegistrarDestroyed(
+    AcceleratorRegistrarImpl* registrar) {
+  accelerator_registrars_.erase(registrar);
+}
+
 void WindowManagerApplication::Initialize(mojo::ApplicationImpl* app) {
   app_ = app;
   tracing_.Initialize(app);
@@ -68,7 +75,8 @@ void WindowManagerApplication::Initialize(mojo::ApplicationImpl* app) {
 
 bool WindowManagerApplication::ConfigureIncomingConnection(
     mojo::ApplicationConnection* connection) {
-  connection->AddService(this);
+  connection->AddService<mus::mojom::AcceleratorRegistrar>(this);
+  connection->AddService<mus::mojom::WindowManager>(this);
   return true;
 }
 
@@ -79,7 +87,12 @@ void WindowManagerApplication::OnAccelerator(uint32_t id,
       window_tree_host_->ActivateNextWindow();
       break;
     default:
-      NOTREACHED() << "Unknown accelerator command: " << id;
+      for (auto* registrar : accelerator_registrars_) {
+        if (registrar->OwnsAccelerator(id)) {
+          registrar->ProcessAccelerator(id, event.Pass());
+          break;
+        }
+      }
   }
 }
 
@@ -116,6 +129,24 @@ void WindowManagerApplication::OnConnectionLost(
 
 void WindowManagerApplication::Create(
     mojo::ApplicationConnection* connection,
+    mojo::InterfaceRequest<mus::mojom::AcceleratorRegistrar> request) {
+  static int accelerator_registrar_count = 0;
+  if (accelerator_registrar_count == std::numeric_limits<int>::max()) {
+    // Restart from zero if we have reached the limit. It is technically
+    // possible to end up with multiple active registrars with the same
+    // namespace, but it is highly unlikely. In the event that multiple
+    // registrars have the same namespace, this new registrar will be unable to
+    // install accelerators.

[Ben Goodger (Google), 2015/12/02 00:59:45]

how is this enforced? you don't seem to prevent registration.

[sadrul, 2015/12/02 19:14:25]

Ah, you are right. We do not actually do the right thing in
WindowTreeHostImpl/EventDispatcher when a dup accelerator is registered. I have
put up https://codereview.chromium.org/1487333004/, which we can use here to
notify the client when registering an accelerator fails.

However, I am not sure if this completely addresses this issue. For example,
some accelerators of the second client with the dup namespace can successfully
be registered, while attempting to register some others may fail (it depends on
what acceletators the first client had installed). I feel like that's a
reasonable expectation for the client, but I could be convinced otherwise. WDYT?

+    accelerator_registrar_count = 0;
+  }
+  accelerator_registrars_.insert(new AcceleratorRegistrarImpl(
+      window_tree_host_.get(), ++accelerator_registrar_count, request.Pass(),
+      base::Bind(&WindowManagerApplication::OnAcceleratorRegistrarDestroyed,
+                 base::Unretained(this))));
+}
+
+void WindowManagerApplication::Create(
+    mojo::ApplicationConnection* connection,
     mojo::InterfaceRequest<mus::mojom::WindowManager> request) {
   if (root_) {
     window_manager_binding_.AddBinding(window_manager_.get(), request.Pass());