mus: Introduce AcceleratorRegistrar and AcceleratorHandler.

mash/wm/accelerator_registrar_impl.cc

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "mash/wm/accelerator_registrar_impl.h"
+
+#include "base/bind.h"
+#include "components/mus/public/interfaces/window_tree_host.mojom.h"
+
+namespace mash {
+namespace wm {
+
+namespace {
+const int kAcceleratorIdMask = 0xffff;
+}
+
+AcceleratorRegistrarImpl::AcceleratorRegistrarImpl(
+    mus::mojom::WindowTreeHost* host,
+    uint32_t accelerator_namespace,
+    mojo::InterfaceRequest<AcceleratorRegistrar> request,
+    const DestroyCallback& destroy_callback)
+    : host_(host),
+      accelerator_namespace_(accelerator_namespace & 0xffff),
+      binding_(this, request.Pass()),
+      destroy_callback_(destroy_callback) {
+  binding_.set_connection_error_handler(base::Bind(
+      &AcceleratorRegistrarImpl::OnBindingGone, base::Unretained(this)));
+}
+
+AcceleratorRegistrarImpl::~AcceleratorRegistrarImpl() {
+  for (const auto& pair : accelerator_handlers_)
+    host_->RemoveAccelerator(pair.first);
+  destroy_callback_.Run(this);
+}
+
+bool AcceleratorRegistrarImpl::OwnsAccelerator(uint32_t accelerator_id) const {
+  return !!accelerator_handlers_.count(accelerator_id);
+}
+
+void AcceleratorRegistrarImpl::ProcessAccelerator(uint32_t accelerator_id,
+                                                  mus::mojom::EventPtr event) {
+  DCHECK(OwnsAccelerator(accelerator_id));
+  accelerator_handlers_[accelerator_id]->OnAccelerator(
+      accelerator_id & kAcceleratorIdMask, event.Pass());
+}
+
+uint32_t AcceleratorRegistrarImpl::ComputeAcceleratorId(
+    uint32_t accelerator_id) const {
+  return (accelerator_namespace_ << 16) | (accelerator_id & kAcceleratorIdMask);
+}
+
+void AcceleratorRegistrarImpl::OnBindingGone() {
+  binding_.Unbind();

[Ben Goodger (Google), 2015/12/01 16:01:45]

is this necessary?

[sadrul, 2015/12/01 19:18:05]

My initial thought was this wouldn't be necessary. But looks like without this,
binding_.is_bound() on line 93 always returns true.

+  // If there's no outstanding accelerator handler for this namespace, then
+  // destroy it.
+  if (accelerator_handlers_.empty())
+    delete this;
+}
+
+void AcceleratorRegistrarImpl::OnHandlerGone(uint32_t accelerator_id) {
+  RemoveAccelerator(accelerator_id);
+}
+
+void AcceleratorRegistrarImpl::AddAccelerator(
+    uint32_t accelerator_id,
+    mus::mojom::EventMatcherPtr matcher,
+    mus::mojom::AcceleratorHandlerPtr handler,

[Ben Goodger (Google), 2015/12/01 16:01:45]

just thinking about this... passing a new handler here almost makes the id
redundant.

given the (current) cost of message pipes it may be desirable to think about
reducing the number in use. in that sense perhaps it makes sense to have a
SetHandler() method on this interface that allows one handler to be set for all
accelerators for this connection. 

[sadrul, 2015/12/01 19:18:05]

Nice. That makes sense, yeah. Done.

+    const AddAcceleratorCallback& callback) {
+  if ((accelerator_id & kAcceleratorIdMask) != accelerator_id) {
+    // The |accelerator_id| is too large, and it can't be handled correctly.
+    callback.Run(false);
+    return;
+  }
+  uint32_t namespaced_accelerator_id = ComputeAcceleratorId(accelerator_id);
+  handler.set_connection_error_handler(
+      base::Bind(&AcceleratorRegistrarImpl::OnHandlerGone,
+                 base::Unretained(this), accelerator_id));
+  accelerator_handlers_.insert(
+      std::make_pair(namespaced_accelerator_id, handler.Pass()));
+  host_->AddAccelerator(namespaced_accelerator_id, matcher.Pass());
+  callback.Run(true);
+}
+
+void AcceleratorRegistrarImpl::RemoveAccelerator(uint32_t accelerator_id) {
+  uint32_t namespaced_accelerator_id = ComputeAcceleratorId(accelerator_id);
+  if (!accelerator_handlers_.count(namespaced_accelerator_id))
+    return;
+  host_->RemoveAccelerator(namespaced_accelerator_id);
+  accelerator_handlers_.erase(namespaced_accelerator_id);
+  // If the registrar is not bound anymore (i.e. the client can no longer
+  // install new accelerators), and the last accelerator has been removed, then
+  // there's no point keeping this alive anymore.
+  if (accelerator_handlers_.empty() && !binding_.is_bound())
+    delete this;
+}
+
+}  // namespace wm
+}  // namespace mash