Screen readers should not say alert for keyword hint message

An alert is more suited to situations where the message is not directly related to the user's input.

Bug: None
Change-Id: I4de40267e7aab8ffd4bca5e7efa104591ea04c2b
Reviewed-on: https://chromium-review.googlesource.com/956846
Commit-Queue: Aaron Leventhal <aleventhal@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542352}

chrome/browser/ui/views/location_bar/keyword_hint_view.cc

@@ -67,7 +67,7 @@ KeywordHintView::KeywordHintView(views::ButtonListener* listener,
 
   // Use leaf alert role so that name is spoken by screen reader, but redundant
   // child label text is not also spoken.
-  GetViewAccessibility().OverrideRole(ax::mojom::Role::kAlert);
+  GetViewAccessibility().OverrideRole(ax::mojom::Role::kGenericContainer);
   GetViewAccessibility().OverrideIsLeaf();
 }
 
@@ -125,8 +125,8 @@ void KeywordHintView::SetKeyword(const base::string16& keyword) {
                       trailing_label_->text());
   }
 
-  // Fire an accessibility alert event, causing the hint to be spoken.
-  NotifyAccessibilityEvent(ax::mojom::Event::kAlert, true);
+  // Fire an accessibility event, causing the hint to be spoken.
+  NotifyAccessibilityEvent(ax::mojom::Event::kLiveRegionChanged, true);
 }
 
 gfx::Size KeywordHintView::CalculatePreferredSize() const {

ui/accessibility/platform/ax_platform_node_win.cc

@@ -3566,6 +3566,8 @@ int AXPlatformNodeWin::MSAAEvent(ax::mojom::Event event) {
     case ax::mojom::Event::kFocus:
     case ax::mojom::Event::kFocusContext:
       return EVENT_OBJECT_FOCUS;
+    case ax::mojom::Event::kLiveRegionChanged:
+      return EVENT_OBJECT_LIVEREGIONCHANGED;
     case ax::mojom::Event::kMenuStart:
       return EVENT_SYSTEM_MENUSTART;
     case ax::mojom::Event::kMenuEnd: