Forward accessibility events to the automation extension process.

chrome/browser/extensions/api/automation_internal/automation_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 "chrome/browser/extensions/api/automation_internal/automation_event_router.h"
+
+#include <string>
+#include <utility>
+
+#include "base/stl_util.h"
+#include "base/values.h"
+#include "chrome/browser/accessibility/ax_tree_id_registry.h"
+#include "chrome/common/extensions/api/automation_internal.h"
+#include "chrome/common/extensions/chrome_extension_messages.h"
+#include "content/public/browser/notification_service.h"
+#include "content/public/browser/notification_source.h"
+#include "content/public/browser/notification_types.h"
+#include "content/public/browser/render_process_host.h"
+#include "extensions/browser/event_router.h"
+#include "ui/accessibility/ax_enums.h"
+#include "ui/accessibility/ax_node_data.h"
+
+namespace extensions {
+
+struct AutomationListener {
+  int routing_id;
+  int process_id;
+  bool desktop;
+  std::set<int> tree_ids;
+};
+
+// static
+AutomationEventRouter* AutomationEventRouter::GetInstance() {
+  return Singleton<AutomationEventRouter,
+                   LeakySingletonTraits<AutomationEventRouter>>::get();
+}
+
+AutomationEventRouter::AutomationEventRouter() {
+  registrar_.Add(this, content::NOTIFICATION_RENDERER_PROCESS_TERMINATED,
+                 content::NotificationService::AllBrowserContextsAndSources());
+  registrar_.Add(this, content::NOTIFICATION_RENDERER_PROCESS_CLOSED,
+                 content::NotificationService::AllBrowserContextsAndSources());
+}
+
+AutomationEventRouter::~AutomationEventRouter() {
+  STLDeleteContainerPairSecondPointers(listener_map_.begin(),
+                                       listener_map_.end());
+}
+
+void AutomationEventRouter::AddListener(
+    ExtensionId extension_id,
+    int ax_tree_id,
+    int process_id,
+    int routing_id,
+    bool desktop) {
+  auto iter = listener_map_.find(extension_id);
+  AutomationListener* listener;

[not at google - send to devlin, 2015/06/02 23:59:24]

it's nice to initialize pointers to nullptr

[dmazzoni, 2015/06/04 20:07:39]

Done.

+  if (iter != listener_map_.end()) {
+    listener = iter->second;

[not at google - send to devlin, 2015/06/02 23:59:24]

What happens if the listener that is already there has a different routing ID?
or ax_tree_id? or whatever? I find the contract of this method, whatever it is,
confusing.

[dmazzoni, 2015/06/04 20:07:39]

OK, I tried to clarify it. I realized it was a mistake to key on the extension
ID because there can be two extension processes corresponding to the same ID in
different browser contexts. I changed it to a vector with the process id and
routing id uniquely identifying the listener, and the other parameters
identifying the trees it wants to listen to.

+  } else {
+    listener = new AutomationListener();
+    listener->routing_id = routing_id;
+    listener->process_id = process_id;
+    listener->desktop = desktop;
+    listener_map_.insert(std::make_pair(extension_id, listener));

[not at google - send to devlin, 2015/06/02 23:59:24]

I would have thought that listener_map_[extension_id] = listener is easier to
write?

[dmazzoni, 2015/06/04 20:07:39]

Doesn't compile, but moot as I simplified it.

+  }
+  listener->tree_ids.insert(ax_tree_id);
+}
+
+void AutomationEventRouter::DispatchAccessibilityEventToAutomation(
+    const ExtensionMsg_AccessibilityEventParams& params) {
+  for (auto iter = listener_map_.begin();
+       iter != listener_map_.end();
+       ++iter) {

[not at google - send to devlin, 2015/06/02 23:59:24]

You can use a range-based for loop here, I think?

[dmazzoni, 2015/06/04 20:07:39]

Done.

+    AutomationListener* listener = iter->second;
+    if (!listener->desktop &&
+        listener->tree_ids.find(params.tree_id) == listener->tree_ids.end()) {
+      continue;
+    }
+
+    content::RenderProcessHost* rph =
+        content::RenderProcessHost::FromID(listener->process_id);
+    rph->Send(
+        new ExtensionMsg_AccessibilityEvent(listener->routing_id, params));
+  }
+}
+
+void AutomationEventRouter::DispatchTreeDestroyedEventToAutomation(
+    int process_id,
+    int routing_id,
+    content::BrowserContext* browser_context) {
+  int tree_id = AXTreeIDRegistry::GetInstance()->GetOrCreateAXTreeID(
+      process_id, routing_id);
+
+  std::string event_name(
+      api::automation_internal::OnAccessibilityTreeDestroyed::kEventName);
+  scoped_ptr<base::ListValue> args(
+      api::automation_internal::OnAccessibilityTreeDestroyed::Create(tree_id));
+  if (browser_context && EventRouter::Get(browser_context)) {

[not at google - send to devlin, 2015/06/02 23:59:24]

Checking for |browser_context| here implies it can be null, could you document
why?

[dmazzoni, 2015/06/04 20:07:39]

Hmmm, I can't see a good reason why. The caller should just handle
AXTreeIDRegistry::GetInstance()->RemoveAXTreeID instead of this function if
there's no browser context.

Check it now.

+    scoped_ptr<Event> event(new Event(event_name, args.Pass()));
+    event->restrict_to_browser_context = browser_context;
+    EventRouter::Get(browser_context)->BroadcastEvent(event.Pass());
+  }
+  AXTreeIDRegistry::GetInstance()->RemoveAXTreeID(tree_id);
+}
+
+void AutomationEventRouter::Observe(
+    int type,
+    const content::NotificationSource& source,
+    const content::NotificationDetails& details) {
+  if (type != content::NOTIFICATION_RENDERER_PROCESS_TERMINATED &&
+      type != content::NOTIFICATION_RENDERER_PROCESS_CLOSED) {
+    NOTREACHED();
+    return;
+  }
+
+  content::RenderProcessHost* rph =
+      content::Source<content::RenderProcessHost>(source).ptr();
+  int process_id = rph->GetID();
+
+  auto iter = listener_map_.begin();
+  while (iter != listener_map_.end()) {
+    auto temp = iter;

[not at google - send to devlin, 2015/06/02 23:59:24]

apologies for nit, but for what it's worth I've more commonly seen this written
as:

for (auto iter = listener_map_.begin(); iter != listener_map_.end();) {
  if (iter->second->process_id = process_id)
    listener_map_.erase(iter++);
  else
    ++iter;
}

[dmazzoni, 2015/06/04 20:07:39]

Thanks, that's cleaner.

+    iter++;
+    if (temp->second->process_id == process_id) {
+      delete temp->second;
+      listener_map_.erase(temp);
+    }
+  }
+}
+
+}  // namespace extensions