[Android] Add accessibility announcement when switching tab models

chrome/android/java/src/org/chromium/chrome/browser/widget/accessibility/AccessibilityTabModelWrapper.java

Index: chrome/android/java/src/org/chromium/chrome/browser/widget/accessibility/AccessibilityTabModelWrapper.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/widget/accessibility/AccessibilityTabModelWrapper.java b/chrome/android/java/src/org/chromium/chrome/browser/widget/accessibility/AccessibilityTabModelWrapper.java
index 0cdc29159e36dbef00c1fd9e932929b7eb4962e7..2c966fcef3894ab2084aa74b23678a58b43e3290 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/widget/accessibility/AccessibilityTabModelWrapper.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/widget/accessibility/AccessibilityTabModelWrapper.java
@@ -62,6 +62,12 @@ public class AccessibilityTabModelWrapper extends LinearLayout {
                     mTabModelSelector.commitAllTabClosures();
                     mTabModelSelector.selectModel(mIncognito);
                     setStateBasedOnModel();
+
+                    int stackAnnouncementId = mIncognito
+                            ? R.string.accessibility_tab_switcher_incognito_stack_selected
+                            : R.string.accessibility_tab_switcher_standard_stack_selected;
+                    AccessibilityTabModelWrapper.this.announceForAccessibility(
+                            getResources().getString(stackAnnouncementId));
                 }
             }
         }