Disable accessibility on Chrome OS when all extension clients are gone

R=dmazzoni@chromium.org

Change-Id: I345f38507ab27b6d5fabb6a3f989973b861ee1f5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2718488
Commit-Queue: David Tseng <dtseng@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#857472}

chrome/browser/ui/aura/accessibility/automation_manager_aura.cc

@@ -71,13 +71,22 @@ void AutomationManagerAura::Enable() {
       PostEvent(focus->GetUniqueId(), ax::mojom::Event::kChildrenChanged);
   }
 #endif
+
+  if (!automation_event_router_observer_.IsObserving()) {
+    automation_event_router_observer_.Observe(
+        extensions::AutomationEventRouter::GetInstance());
+  }
 }
 
 void AutomationManagerAura::Disable() {
   enabled_ = false;
   cache_ = std::make_unique<views::AXAuraObjCache>();
   tree_.reset();
-  Reset(true);
+  tree_serializer_.reset();
+  alert_window_.reset();
+
+  if (automation_event_router_observer_.IsObserving())
+    automation_event_router_observer_.Reset();
 }
 
 void AutomationManagerAura::OnViewEvent(views::View* view,
@@ -94,6 +103,10 @@ void AutomationManagerAura::OnViewEvent(views::View* view,
   PostEvent(obj->GetUniqueId(), event_type);
 }
 
+void AutomationManagerAura::AllAutomationExtensionsGone() {
+  Disable();
+}
+
 void AutomationManagerAura::HandleEvent(ax::mojom::Event event_type) {
   views::AXAuraObjWrapper* obj = tree_->GetRoot();
   if (!obj)

chrome/browser/ui/aura/accessibility/automation_manager_aura.h

@@ -13,6 +13,8 @@
 #include <vector>
 
 #include "base/macros.h"
+#include "base/scoped_observation.h"
+#include "extensions/browser/api/automation_internal/automation_event_router.h"
 #include "ui/accessibility/ax_action_handler.h"
 #include "ui/accessibility/ax_tree_serializer.h"
 #include "ui/views/accessibility/ax_aura_obj_cache.h"
@@ -39,7 +41,8 @@ using AuraAXTreeSerializer = ui::AXTreeSerializer<views::AXAuraObjWrapper*>;
 // Manages a tree of automation nodes backed by aura constructs.
 class AutomationManagerAura : public ui::AXActionHandler,
                               public views::AXAuraObjCache::Delegate,
-                              public views::AXEventObserver {
+                              public views::AXEventObserver,
+                              public extensions::AutomationEventRouterObserver {
  public:
   // Get the single instance of this class.
   static AutomationManagerAura* GetInstance();
@@ -69,6 +72,9 @@ class AutomationManagerAura : public ui::AXActionHandler,
   // views::AXEventObserver:
   void OnViewEvent(views::View* view, ax::mojom::Event event_type) override;
 
+  // AutomationEventRouterObserver:
+  void AllAutomationExtensionsGone() override;
+
   void set_event_bundle_sink(ui::AXEventBundleSink* sink) {
     event_bundle_sink_ = sink;
   }
@@ -137,6 +143,10 @@ class AutomationManagerAura : public ui::AXActionHandler,
 
   bool is_performing_action_ = false;
 
+  base::ScopedObservation<extensions::AutomationEventRouter,
+                          extensions::AutomationEventRouterObserver>
+      automation_event_router_observer_{this};
+
   DISALLOW_COPY_AND_ASSIGN(AutomationManagerAura);
 };
 

extensions/browser/api/automation_internal/automation_event_router.cc

@@ -47,7 +47,7 @@ AutomationEventRouter::AutomationEventRouter()
 #endif
 }
 
-AutomationEventRouter::~AutomationEventRouter() {}
+AutomationEventRouter::~AutomationEventRouter() = default;
 
 void AutomationEventRouter::RegisterListenerForOneTree(
     const ExtensionId& extension_id,
@@ -170,12 +170,22 @@ void AutomationEventRouter::DispatchGetTextLocationDataResult(
       ->DispatchEventToExtension(data.source_extension_id, std::move(event));
 }
 
-AutomationEventRouter::AutomationListener::AutomationListener() {}
+void AutomationEventRouter::AddObserver(
+    AutomationEventRouterObserver* observer) {
+  observers_.AddObserver(observer);
+}
+
+void AutomationEventRouter::RemoveObserver(
+    AutomationEventRouterObserver* observer) {
+  observers_.RemoveObserver(observer);
+}
+
+AutomationEventRouter::AutomationListener::AutomationListener() = default;
 
 AutomationEventRouter::AutomationListener::AutomationListener(
     const AutomationListener& other) = default;
 
-AutomationEventRouter::AutomationListener::~AutomationListener() {}
+AutomationEventRouter::AutomationListener::~AutomationListener() = default;
 
 void AutomationEventRouter::Register(const ExtensionId& extension_id,
                                      int listener_process_id,
@@ -238,6 +248,11 @@ void AutomationEventRouter::RenderProcessHostDestroyed(
   });
   rph_observers_.Remove(host);
   UpdateActiveProfile();
+
+  if (rph_observers_.GetSourcesCount() == 0) {
+    for (AutomationEventRouterObserver& observer : observers_)
+      observer.AllAutomationExtensionsGone();
+  }
 }
 
 void AutomationEventRouter::UpdateActiveProfile() {

extensions/browser/api/automation_internal/automation_event_router.h

@@ -35,6 +35,11 @@ struct ExtensionMsg_AccessibilityLocationChangeParams;
 namespace extensions {
 struct AutomationListener;
 
+class AutomationEventRouterObserver {
+ public:
+  virtual void AllAutomationExtensionsGone() = 0;
+};
+
 class AutomationEventRouter : public ui::AXEventBundleSink,
                               public content::RenderProcessHostObserver,
                               public AutomationEventRouterInterface {
@@ -78,6 +83,9 @@ class AutomationEventRouter : public ui::AXEventBundleSink,
       const ui::AXActionData& data,
       const base::Optional<gfx::Rect>& rect) override;
 
+  void AddObserver(AutomationEventRouterObserver* observer);
+  void RemoveObserver(AutomationEventRouterObserver* observer);
+
  private:
   struct AutomationListener {
     AutomationListener();
@@ -131,6 +139,8 @@ class AutomationEventRouter : public ui::AXEventBundleSink,
   ScopedObserver<content::RenderProcessHost, content::RenderProcessHostObserver>
       rph_observers_{this};
 
+  base::ObserverList<AutomationEventRouterObserver>::Unchecked observers_;
+
   friend struct base::DefaultSingletonTraits<AutomationEventRouter>;
 
   DISALLOW_COPY_AND_ASSIGN(AutomationEventRouter);

extensions/browser/api/automation_internal/automation_internal_api.cc

@@ -11,6 +11,7 @@
 
 #include "base/bind.h"
 #include "base/macros.h"
+#include "base/scoped_observation.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
@@ -140,9 +141,12 @@ base::LazyInstance<OldAXTreeIdMap>::DestructorAtExit g_old_ax_tree =
 // Helper class that receives accessibility data from |WebContents|.
 class AutomationWebContentsObserver
     : public content::WebContentsObserver,
-      public content::WebContentsUserData<AutomationWebContentsObserver> {
+      public content::WebContentsUserData<AutomationWebContentsObserver>,
+      public AutomationEventRouterObserver {
  public:
-  ~AutomationWebContentsObserver() override {}
+  ~AutomationWebContentsObserver() override {
+    automation_event_router_observer_.Reset();
+  }
 
   // content::WebContentsObserver overrides.
   void AccessibilityEventReceived(const content::AXEventNotificationDetails&
@@ -232,6 +236,17 @@ class AutomationWebContentsObserver
     AccessibilityEventReceived(content_event_bundle);
   }
 
+  // AutomationEventRouterObserver overrides.
+  void AllAutomationExtensionsGone() override {
+    if (!web_contents())
+      return;
+
+    ui::AXMode new_mode = web_contents()->GetAccessibilityMode();
+    uint8_t flags = ui::kAXModeWebContentsOnly.mode();
+    new_mode.set_mode(flags, false);
+    web_contents()->SetAccessibilityMode(std::move(new_mode));
+  }
+
  private:
   friend class content::WebContentsUserData<AutomationWebContentsObserver>;
 
@@ -250,10 +265,17 @@ class AutomationWebContentsObserver
           ax::mojom::Event::kMediaStartedPlaying;
       AccessibilityEventReceived(content_event_bundle);
     }
+
+    automation_event_router_observer_.Observe(
+        AutomationEventRouter::GetInstance());
   }
 
   content::BrowserContext* browser_context_;
 
+  base::ScopedObservation<extensions::AutomationEventRouter,
+                          extensions::AutomationEventRouterObserver>
+      automation_event_router_observer_{this};
+
   WEB_CONTENTS_USER_DATA_KEY_DECL();
 
   DISALLOW_COPY_AND_ASSIGN(AutomationWebContentsObserver);