Adds increment/decrement actions to fuchsia accessibility bridge. (flutter#21049)

Author: abrush21

shell/platform/fuchsia/flutter/accessibility_bridge.cc

@@ -356,6 +356,10 @@ AccessibilityBridge::GetFlutterSemanticsAction(
     // Scroll node to make it visible.
     case fuchsia::accessibility::semantics::Action::SHOW_ON_SCREEN:
       return flutter::SemanticsAction::kShowOnScreen;
+    case fuchsia::accessibility::semantics::Action::INCREMENT:
+      return flutter::SemanticsAction::kIncrease;
+    case fuchsia::accessibility::semantics::Action::DECREMENT:
+      return flutter::SemanticsAction::kDecrease;
     default:
       FML_DLOG(WARNING) << "Unexpected action "
                         << static_cast<int32_t>(fuchsia_action)

shell/platform/fuchsia/flutter/accessibility_bridge_unittest.cc

@@ -633,5 +633,19 @@ TEST_F(AccessibilityBridgeTest, Actions) {
       2u, fuchsia::accessibility::semantics::Action::DEFAULT,
       unhandled_callback);
   EXPECT_EQ(accessibility_delegate_.actions.size(), 3u);
+
+  accessibility_bridge_->OnAccessibilityActionRequested(
+      0u, fuchsia::accessibility::semantics::Action::INCREMENT,
+      handled_callback);
+  EXPECT_EQ(accessibility_delegate_.actions.size(), 4u);
+  EXPECT_EQ(accessibility_delegate_.actions.back(),
+            std::make_pair(0, flutter::SemanticsAction::kIncrease));
+
+  accessibility_bridge_->OnAccessibilityActionRequested(
+      0u, fuchsia::accessibility::semantics::Action::DECREMENT,
+      handled_callback);
+  EXPECT_EQ(accessibility_delegate_.actions.size(), 5u);
+  EXPECT_EQ(accessibility_delegate_.actions.back(),
+            std::make_pair(0, flutter::SemanticsAction::kDecrease));
 }
 }  // namespace flutter_runner_test