Avoid superfluous screen reader announcement in device chooser

The USB/Bluetooth device chooser was announcing "No devices available"
even though devices were available. The message also sometimes briefly flashed.

To fix this, wait until data is initialized or initial focus occurs before
showing the message.

This is one part of ongoing work to improve accessibility of this dialog.

Bug: 820351
Change-Id: Ia295b7514725512cf0de539d238402a51e220055
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1970260Reviewed-by: Vincent Scheib <scheib@chromium.org>
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Reviewed-by: Ovidio de Jesús Ruiz-Henríquez <odejesush@chromium.org>
Commit-Queue: Aaron Leventhal <aleventhal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#728560}

chrome/browser/ui/views/device_chooser_content_view.cc

@@ -217,11 +217,13 @@ gfx::ImageSkia DeviceChooserContentView::GetIcon(int row) {
 }
 
 void DeviceChooserContentView::OnOptionsInitialized() {
+  is_initialized_ = true;
   table_view_->OnModelChanged();
   UpdateTableView();
 }
 
 void DeviceChooserContentView::OnOptionAdded(size_t index) {
+  is_initialized_ = true;
   table_view_->OnItemsAdded(base::checked_cast<int>(index), 1);
   UpdateTableView();
 }
@@ -353,10 +355,17 @@ void DeviceChooserContentView::Close() {
 
 void DeviceChooserContentView::UpdateTableView() {
   bool has_options = adapter_enabled_ && RowCount() > 0;
+  if (!is_initialized_ && GetWidget() &&
+      GetWidget()->GetFocusManager()->GetFocusedView()) {
+    is_initialized_ = true;  // Can show no_options_view_ after initial focus.
+  }
   table_parent_->SetVisible(has_options);
   table_view_->SetEnabled(has_options &&
                           !chooser_controller_->TableViewAlwaysDisabled());
-  no_options_view_->SetVisible(!has_options && adapter_enabled_);
+  // Do not set to visible until initialization is complete, in order to prevent
+  // message from briefly flashing and being read by screen reader.
+  no_options_view_->SetVisible(!has_options && adapter_enabled_ &&
+                               is_initialized_);
   adapter_off_view_->SetVisible(!adapter_enabled_);
 }
 

chrome/browser/ui/views/device_chooser_content_view.h

@@ -90,6 +90,8 @@ class DeviceChooserContentView : public views::View,
   views::View* adapter_off_view_ = nullptr;
   BluetoothStatusContainer* bluetooth_status_container_ = nullptr;
 
+  bool is_initialized_ = false;
+
   DISALLOW_COPY_AND_ASSIGN(DeviceChooserContentView);
 };
 

chrome/browser/ui/views/device_chooser_content_view_unittest.cc

@@ -104,13 +104,21 @@ class DeviceChooserContentViewTest : public ChromeViewsTestBase {
   bool IsDeviceSelected() { return !table_view()->selection_model().empty(); }
 
   void ExpectNoDevices() {
-    EXPECT_TRUE(no_options_view()->GetVisible());
     EXPECT_EQ(0, table_view()->GetRowCount());
     // The table should be disabled since there are no (real) options.
     EXPECT_FALSE(table_parent()->GetVisible());
     EXPECT_FALSE(table_view()->GetEnabled());
     EXPECT_FALSE(IsDeviceSelected());
   }
+  void ExpectNoDevicesWithMessageVisible() {
+    EXPECT_TRUE(no_options_view()->GetVisible());
+    ExpectNoDevices();
+  }
+
+  void ExpectNoDevicesWithMessageHidden() {
+    EXPECT_FALSE(no_options_view()->GetVisible());
+    ExpectNoDevices();
+  }
 
  protected:
   std::unique_ptr<views::View> extra_views_container_;
@@ -125,8 +133,7 @@ class DeviceChooserContentViewTest : public ChromeViewsTestBase {
 
 TEST_F(DeviceChooserContentViewTest, InitialState) {
   EXPECT_CALL(table_observer(), OnSelectionChanged()).Times(0);
-
-  ExpectNoDevices();
+  ExpectNoDevicesWithMessageHidden();
   EXPECT_FALSE(adapter_off_view()->GetVisible());
   EXPECT_FALSE(throbber()->GetVisible());
   EXPECT_FALSE(scanning_label()->GetVisible());
@@ -170,7 +177,7 @@ TEST_F(DeviceChooserContentViewTest, RemoveOption) {
   controller()->RemoveDevice(1);
   controller()->RemoveDevice(0);
   // Should be back to the initial state.
-  ExpectNoDevices();
+  ExpectNoDevicesWithMessageVisible();
 }
 
 TEST_F(DeviceChooserContentViewTest, UpdateOption) {
@@ -219,7 +226,7 @@ TEST_F(DeviceChooserContentViewTest, TurnBluetoothOffAndOn) {
   controller()->RemoveDevice(0);
   controller()->SetBluetoothStatus(
       FakeBluetoothChooserController::BluetoothStatus::IDLE);
-  ExpectNoDevices();
+  ExpectNoDevicesWithMessageVisible();
   EXPECT_FALSE(adapter_off_view()->GetVisible());
   EXPECT_FALSE(throbber()->GetVisible());
   EXPECT_FALSE(scanning_label()->GetVisible());