scanner: Add screen reader announcement when standalone app opens.

Add screen reader announcement to describe the standalone app
functionality and how to use keyboard navigation.

Bug: b:398914045
Change-Id: I01c3aebc23590d21689aff4b7497f7ad714d1c28
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6332958
Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Commit-Queue: Michelle Chen <michellegc@google.com>
Cr-Commit-Position: refs/heads/main@{#1430055}

ash/ash_strings.grd

@@ -6727,6 +6727,9 @@ Here are some things you can try to get started.
       <message name="IDS_ASH_SCREEN_CAPTURE_ALERT_OPEN" desc="Alert spoken by screen readers on entering capture mode.">
         Capture Mode, default is <ph name="SOURCE">$1<ex>partial</ex></ph> <ph name="TYPE">$2<ex>screenshot</ex></ph>. Press tab for keyboard navigation.
       </message>
+      <message name="IDS_ASH_SUNFISH_MODE_ALERT_OPEN" desc="Alert spoken by screen readers on entering a mode where users can select a region on their screen to search.">
+        Select to search my screen. Press tab then space for keyboard navigation.
+      </message>
       <message name="IDS_ASH_SCREEN_CAPTURE_SOURCE_FULLSCREEN" desc="Spoken by screen readers for the open alert with the source as full screen.">
         full screen
       </message>

ash/ash_strings_grd/IDS_ASH_SUNFISH_MODE_ALERT_OPEN.png.sha1

@@ -0,0 +1 @@
+9bfa31030f7af942df778c372b65cb740a338d41

ash/capture_mode/capture_mode_behavior.cc

@@ -386,6 +386,9 @@ class SunfishBehavior : public CaptureModeBehavior {
   const std::u16string GetCaptureLabelRegionText() const override {
     return l10n_util::GetStringUTF16(IDS_ASH_SUNFISH_CAPTURE_LABEL);
   }
+  const std::string GetCaptureModeOpenAnnouncement() const override {
+    return l10n_util::GetStringUTF8(IDS_ASH_SUNFISH_MODE_ALERT_OPEN);
+  }
   int GetCaptureBarWidth() const override {
     // Return the height so the button is circular.
     return capture_mode::kCaptureBarHeight;
@@ -623,6 +626,30 @@ const std::u16string CaptureModeBehavior::GetCaptureLabelRegionText() const {
           : IDS_ASH_SCREEN_CAPTURE_LABEL_REGION_VIDEO_RECORD);
 }
 
+const std::string CaptureModeBehavior::GetCaptureModeOpenAnnouncement() const {
+  CaptureModeController* controller = CaptureModeController::Get();
+  int capture_source_id;
+  switch (controller->source()) {
+    case CaptureModeSource::kFullscreen:
+      capture_source_id = IDS_ASH_SCREEN_CAPTURE_SOURCE_FULLSCREEN;
+      break;
+    case CaptureModeSource::kRegion:
+      capture_source_id = IDS_ASH_SCREEN_CAPTURE_SOURCE_PARTIAL;
+      break;
+    case CaptureModeSource::kWindow:
+      capture_source_id = IDS_ASH_SCREEN_CAPTURE_SOURCE_WINDOW;
+      break;
+  }
+
+  return l10n_util::GetStringFUTF8(
+      IDS_ASH_SCREEN_CAPTURE_ALERT_OPEN,
+      l10n_util::GetStringUTF16(capture_source_id),
+      l10n_util::GetStringUTF16(
+          controller->type() == CaptureModeType::kImage
+              ? IDS_ASH_SCREEN_CAPTURE_TYPE_SCREENSHOT
+              : IDS_ASH_SCREEN_CAPTURE_TYPE_SCREEN_RECORDING));
+}
+
 std::unique_ptr<CaptureModeBarView>
 CaptureModeBehavior::CreateCaptureModeBarView() {
   return std::make_unique<NormalCaptureBarView>(this);

ash/capture_mode/capture_mode_behavior.h

@@ -135,6 +135,10 @@ class CaptureModeBehavior {
   // a capture region phase.
   virtual const std::u16string GetCaptureLabelRegionText() const;
 
+  // Returns the text to be announced by a screen reader when capture mode is
+  // opened with this behavior.
+  virtual const std::string GetCaptureModeOpenAnnouncement() const;
+
   // Creates the capture mode bar view, which might look different depending on
   // the actual type of the behavior.
   virtual std::unique_ptr<CaptureModeBarView> CreateCaptureModeBarView();

ash/capture_mode/capture_mode_session.cc

@@ -369,18 +369,6 @@ int GetArrowKeyPressChange(int event_flags) {
   return capture_mode::kArrowKeyboardRegionChangeDp;
 }
 
-// Returns the `message_id` for the chromevox alert when capture session starts.
-int GetMessageIdForInitialCaptureSource(CaptureModeSource source) {
-  switch (source) {
-    case CaptureModeSource::kFullscreen:
-      return IDS_ASH_SCREEN_CAPTURE_SOURCE_FULLSCREEN;
-    case CaptureModeSource::kRegion:
-      return IDS_ASH_SCREEN_CAPTURE_SOURCE_PARTIAL;
-    default:
-      return IDS_ASH_SCREEN_CAPTURE_SOURCE_WINDOW;
-  }
-}
-
 void UpdateFloatingPanelBoundsIfNeeded() {
   Shell::Get()->accessibility_controller()->UpdateFloatingPanelBoundsIfNeeded();
 }
@@ -3834,14 +3822,8 @@ void CaptureModeSession::InitInternal() {
   // Trigger this before creating `capture_mode_bar_widget_` as we want to read
   // out this message before reading out the first view of
   // `capture_mode_bar_widget_`.
-  capture_mode_util::TriggerAccessibilityAlert(l10n_util::GetStringFUTF8(
-      IDS_ASH_SCREEN_CAPTURE_ALERT_OPEN,
-      l10n_util::GetStringUTF16(
-          GetMessageIdForInitialCaptureSource(controller_->source())),
-      l10n_util::GetStringUTF16(
-          controller_->type() == CaptureModeType::kImage
-              ? IDS_ASH_SCREEN_CAPTURE_TYPE_SCREENSHOT
-              : IDS_ASH_SCREEN_CAPTURE_TYPE_SCREEN_RECORDING)));
+  capture_mode_util::TriggerAccessibilityAlert(
+      active_behavior_->GetCaptureModeOpenAnnouncement());
 
   // A context menu may have input capture when entering a session. Remove
   // capture from it, otherwise subsequent mouse events will cause it to close,