Forward accessibility events to the automation extension process.

chrome/browser/extensions/api/automation_internal/automation_event_router.h

+// 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.
+
+#ifndef CHROME_BROWSER_EXTENSIONS_API_AUTOMATION_INTERNAL_AUTOMATION_EVENT_ROUTER_H_
+#define CHROME_BROWSER_EXTENSIONS_API_AUTOMATION_INTERNAL_AUTOMATION_EVENT_ROUTER_H_
+
+#include <vector>
+
+#include "base/memory/singleton.h"
+#include "chrome/common/extensions/api/automation_internal.h"
+#include "content/public/browser/ax_event_notification_details.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
+#include "extensions/common/extension.h"
+
+namespace content {
+class BrowserContext;
+}  // namespace content
+
+struct ExtensionMsg_AccessibilityEventParams;
+
+namespace extensions {
+
+struct AutomationListener;
+
+class AutomationEventRouter : public content::NotificationObserver {
+ public:
+  static AutomationEventRouter* GetInstance();
+
+  // Indicates that the listener at |listener_process_id|, |listener_routing_id|
+  // wants to receive automation events from the accessibility tree indicated
+  // by |source_ax_tree_id|, or all accessibility trees if |desktop| is true.
+  // Automation events are forwarded from now on until the listener process
+  // dies.
+  void AddListener(int listener_process_id,

[not at google - send to devlin, 2015/06/04 23:03:28]

A name like "AddListener" implies to me that it should take a Listener or a
base::Callback as a parameter, i.e. that the listener is an actual object. Maybe
"Register" or something at least. Or "StartForwarding".

[dmazzoni, 2015/06/08 18:02:57]

I like "Register", since the name of the class (AutomationEventListener)
explains a lot of what it means now.

+                   int listener_routing_id,
+                   int source_ax_tree_id,
+                   bool desktop);

[not at google - send to devlin, 2015/06/04 23:03:28]

On reading call sites, I'd find it nicer if this were an enum of DESKTOP and
TAB. Or alternatively 2 different methods
StartForwardingFromTab/StartForwardingFromDesktop (or whatever) since only the
Tab version needs the tree ID right?

[dmazzoni, 2015/06/08 18:02:57]

Sure. Made into two methods.

+
+  void DispatchAccessibilityEventToAutomation(

[not at google - send to devlin, 2015/06/04 23:03:28]

Well I'd drop the "ToAutomation", but up to you.

[dmazzoni, 2015/06/08 18:02:57]

Done.

+      const ExtensionMsg_AccessibilityEventParams& params);
+
+  // Notify all automation extensions that an accessibility tree was
+  // destroyed. If |browser_context| is null,
+  void DispatchTreeDestroyedEventToAutomation(
+      int tree_id,
+      content::BrowserContext* browser_context);
+
+ private:
+  struct AutomationListener {
+    AutomationListener();
+    ~AutomationListener();
+
+    int routing_id;
+    int process_id;
+    bool desktop;
+    std::set<int> tree_ids;
+  };
+
+  AutomationEventRouter();
+  ~AutomationEventRouter() override;
+
+  // content::NotificationObserver interface.
+  void Observe(int type,
+               const content::NotificationSource& source,
+               const content::NotificationDetails& details) override;
+
+  content::NotificationRegistrar registrar_;
+  std::vector<AutomationListener> listeners_;
+
+  friend struct DefaultSingletonTraits<AutomationEventRouter>;
+
+  DISALLOW_COPY_AND_ASSIGN(AutomationEventRouter);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_API_AUTOMATION_INTERNAL_AUTOMATION_EVENT_ROUTER_H_