Plumbing from WebPresentationClient to the Presentation Mojo service for

content/renderer/presentation/presentation_dispatcher.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 "content/renderer/presentation/presentation_dispatcher.h"
+
+#include "content/public/common/service_registry.h"
+#include "content/public/renderer/render_frame.h"
+#include "third_party/WebKit/public/platform/WebPresentationController.h"
+
+namespace content {
+
+PresentationDispatcher::PresentationDispatcher(RenderFrame* render_frame)
+    : RenderFrameObserver(render_frame) {}
+
+PresentationDispatcher::~PresentationDispatcher() {}
+
+void PresentationDispatcher::setController(
+    blink::WebPresentationController* controller) {
+  controller_ = controller;
+}
+
+void PresentationDispatcher::addDeviceAvailabilityListener() {
+  ConnectToPresentationServiceIfNeeded();
+  presentation_service_->AddDeviceAvailabilityListener();
+}
+
+void PresentationDispatcher::removeDeviceAvailabilityListener() {
+  ConnectToPresentationServiceIfNeeded();
+  presentation_service_->RemoveDeviceAvailabilityListener();
+}
+
+void PresentationDispatcher::DeviceAvailabilityChanged(bool available) {
+  if (controller_)
+    controller_->didChangeAvailability(available);
+}
+
+void PresentationDispatcher::ConnectToPresentationServiceIfNeeded() {
+  if (!presentation_service_.get()) {

[Peter Beverloo, 2015/01/07 19:41:21]

nit: I'd prefer early returns over a block like this encapsulating the
function's entire body.

[whywhat, 2015/01/08 17:28:53]

Done.

+    render_frame()->GetServiceRegistry()->ConnectToRemoteService(
+        &presentation_service_);
+    presentation_service_.set_client(this);
+  }
+}
+
+}  // namespace content