Introduce chrome.displaySource API

extensions/browser/api/display_source/display_source_event_router.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 "extensions/browser/api/display_source/display_source_event_router.h"
+
+#include "content/public/browser/browser_context.h"
+#include "extensions/browser/api/display_source/display_source_api.h"
+#include "extensions/browser/api/display_source/display_source_connection_delegate.h"
+#include "extensions/browser/api/display_source/display_source_connection_delegate_factory.h"
+#include "extensions/common/api/display_source.h"
+
+namespace extensions {
+
+class DisplaySourceEventRouterImpl
+    : public DisplaySourceEventRouter,
+      public DisplaySourceConnectionDelegate::Observer {
+ public:
+  explicit DisplaySourceEventRouterImpl(
+      content::BrowserContext* browser_context);
+  ~DisplaySourceEventRouterImpl() override;
+
+ protected:
+  // KeyedService overrides:
+  void Shutdown() override;
+
+  // EventRouter::Observer overrides:
+  void OnListenerAdded(const EventListenerInfo& details) override;
+  void OnListenerRemoved(const EventListenerInfo& details) override;
+
+  // DisplaySourceConnectionDelegate::Observer overrides:
+  void OnSinksUpdated(const DisplaySourceSinkInfoList& sinks) override;
+
+ private:
+  void StartOrStopListeningForSinksChanges();
+
+  content::BrowserContext* browser_context_;
+  bool listening_;
+
+  DISALLOW_COPY_AND_ASSIGN(DisplaySourceEventRouterImpl);
+};
+
+DisplaySourceEventRouterImpl::DisplaySourceEventRouterImpl(
+    content::BrowserContext* browser_context)
+    : browser_context_(browser_context), listening_(false) {
+  EventRouter* event_router = EventRouter::Get(browser_context_);
+  if (!event_router)
+    return;
+  event_router->RegisterObserver(
+      this, api::display_source::OnSinksUpdated::kEventName);
+}
+
+DisplaySourceEventRouterImpl::~DisplaySourceEventRouterImpl() {
+  DCHECK(!listening_);
+}
+
+void DisplaySourceEventRouterImpl::Shutdown() {
+  EventRouter* event_router = EventRouter::Get(browser_context_);
+  if (event_router)
+    event_router->UnregisterObserver(this);
+
+  if (!listening_)
+    return;
+  listening_ = false;
+  DisplaySourceConnectionDelegate* delegate =
+      DisplaySourceConnectionDelegateFactory::GetForBrowserContext(
+          browser_context_);
+  if (delegate)
+    delegate->RemoveObserver(this);
+}
+
+void DisplaySourceEventRouterImpl::OnListenerAdded(
+    const EventListenerInfo& details) {
+  StartOrStopListeningForSinksChanges();
+}
+
+void DisplaySourceEventRouterImpl::OnListenerRemoved(
+    const EventListenerInfo& details) {
+  StartOrStopListeningForSinksChanges();
+}
+
+void DisplaySourceEventRouterImpl::StartOrStopListeningForSinksChanges() {
+  EventRouter* event_router = EventRouter::Get(browser_context_);
+  if (!event_router)
+    return;
+
+  bool should_listen = event_router->HasEventListener(
+      api::display_source::OnSinksUpdated::kEventName);
+  if (should_listen && !listening_) {
+    DisplaySourceConnectionDelegate* delegate =
+        DisplaySourceConnectionDelegateFactory::GetForBrowserContext(
+            browser_context_);
+    if (delegate) {
+      delegate->AddObserver(this);
+      delegate->StartWatchingSinks();
+    }
+  }
+  if (!should_listen && listening_) {
+    DisplaySourceConnectionDelegate* delegate =
+        DisplaySourceConnectionDelegateFactory::GetForBrowserContext(
+            browser_context_);
+    if (delegate) {
+      delegate->RemoveObserver(this);
+      delegate->StopWatchingSinks();
+    }
+  }
+
+  listening_ = should_listen;
+}
+
+void DisplaySourceEventRouterImpl::OnSinksUpdated(
+    const DisplaySourceSinkInfoList& sinks) {
+  EventRouter* event_router = EventRouter::Get(browser_context_);
+  if (!event_router)
+    return;
+  scoped_ptr<base::ListValue> args(
+      api::display_source::OnSinksUpdated::Create(sinks));
+  scoped_ptr<Event> sinks_updated_event(
+      new Event(events::DISPLAY_SOURCE_ON_SINKS_UPDATED,
+                api::display_source::OnSinksUpdated::kEventName, args.Pass()));
+  event_router->BroadcastEvent(sinks_updated_event.Pass());
+}
+
+DisplaySourceEventRouter* DisplaySourceEventRouter::Create(
+    content::BrowserContext* browser_context) {
+  return new DisplaySourceEventRouterImpl(browser_context);

[asargent_no_longer_on_chrome, 2015/11/17 00:51:56]

Do we need to have the fancy extra indirection of a DisplaySourceEventRouter and
 DisplaySourceEventRouterImpl, instead of just having the functionality from
DisplaySourceEventRouterImpl live in DisplaySourceEventRouter? Usually we only
do that when there could be more than one implementation.

[Mikhail, 2015/11/17 14:07:42]

It just hides out the implementation details, but we can do without this
indirection

+}
+
+}  // namespace extensions