ChromeVox: Disable following a11y events after screen off alert is received

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

Index: chrome/browser/ui/aura/accessibility/automation_manager_aura.cc
diff --git a/chrome/browser/ui/aura/accessibility/automation_manager_aura.cc b/chrome/browser/ui/aura/accessibility/automation_manager_aura.cc
index 06bfc0f172ca4a6c131908e5f44ce4aa609f4ea8..8a1e53cf83383cbba5dfefee968683e48c5d7ad5 100644
--- a/chrome/browser/ui/aura/accessibility/automation_manager_aura.cc
+++ b/chrome/browser/ui/aura/accessibility/automation_manager_aura.cc
@@ -14,12 +14,14 @@
 #include "chrome/browser/extensions/api/automation_internal/automation_event_router.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/common/extensions/chrome_extension_messages.h"
+#include "chrome/grit/generated_resources.h"
 #include "content/public/browser/ax_event_notification_details.h"
 #include "content/public/browser/browser_context.h"
 #include "ui/accessibility/ax_action_data.h"
 #include "ui/accessibility/ax_enums.h"
 #include "ui/aura/env.h"
 #include "ui/aura/window.h"
+#include "ui/base/l10n/l10n_util.h"
 #include "ui/views/accessibility/ax_aura_obj_wrapper.h"
 #include "ui/views/view.h"
 #include "ui/views/widget/widget.h"
@@ -31,6 +33,18 @@
 using content::BrowserContext;
 using extensions::AutomationEventRouter;
 
+namespace {
+
+bool IsScreenOffAlert(const std::string& text) {
+  return text == l10n_util::GetStringUTF8(IDS_A11Y_ALERT_SCREEN_OFF);
+}
+
+bool IsScreenOnAlert(const std::string& text) {
+  return text == l10n_util::GetStringUTF8(IDS_A11Y_ALERT_SCREEN_ON);
+}
+
+}  // namespace
+
 // static
 AutomationManagerAura* AutomationManagerAura::GetInstance() {
   return base::Singleton<AutomationManagerAura>::get();
@@ -76,13 +90,18 @@ void AutomationManagerAura::HandleEvent(BrowserContext* context,
 
 void AutomationManagerAura::HandleAlert(content::BrowserContext* context,
                                         const std::string& text) {
-  if (!enabled_)
+  if (!enabled_ && !IsScreenOnAlert(text))
     return;
 
   views::AXAuraObjWrapper* obj =
       static_cast<AXRootObjWrapper*>(current_tree_->GetRoot())
           ->GetAlertForText(text);
   SendEvent(context, obj, ui::AX_EVENT_ALERT);
+
+  if (IsScreenOffAlert(text))

[David Tseng, 2017/02/03 00:27:15]

I wouldn't want to check against this string every single time an alert gets
fired.

How about adding AutomationManagerAura to subscribe to screen on/off
notifications? 

[Qiang(Joe) Xu, 2017/02/03 02:46:54]

Screen on/off info may come from chromeos::power_manager_client. Power button
event is processed in ash/. I feel it has code dependency issue and timing
issue.

Another way is ChromeShellDelegate::TriggerAccessibilityAlert to pass in the
screen on/off information of the alert. WDYT?

+    Disable();
+  else if (IsScreenOnAlert(text))
+    Enable(context);
 }
 
 void AutomationManagerAura::PerformAction(