MacViews a11y: Allow accessibility clients to set the AXValue on some controls.

ui/views/widget/native_widget_mac_accessibility_unittest.mm

Index: ui/views/widget/native_widget_mac_accessibility_unittest.mm
diff --git a/ui/views/widget/native_widget_mac_accessibility_unittest.mm b/ui/views/widget/native_widget_mac_accessibility_unittest.mm
index a95cf0ad3f595956c94771b595f3fb05656a0e0f..8f224aa37768d8d07e59c3ae67f668a1fe1c1b1e 100644
--- a/ui/views/widget/native_widget_mac_accessibility_unittest.mm
+++ b/ui/views/widget/native_widget_mac_accessibility_unittest.mm
@@ -304,4 +304,38 @@ TEST_F(NativeWidgetMacAccessibilityTest, TextfieldEditableAttributes) {
                 NSAccessibilityVisibleCharacterRangeAttribute) rangeValue]));
 }
 
+// Test writing accessibility attributes via an accessibility client.
+TEST_F(NativeWidgetMacAccessibilityTest, TextfieldWritableAttributes) {
+  Textfield* textfield = AddChildTextfield(GetWidgetBounds().size());
+
+  // Get the textfield accessibility object.
+  NSPoint midpoint = gfx::ScreenPointToNSPoint(GetWidgetBounds().CenterPoint());
+  id ax_node = [widget()->GetNativeWindow() accessibilityHitTest:midpoint];
+  EXPECT_TRUE(ax_node);
+
+  // Make sure it's the correct accessibility object.
+  id value =
+      [ax_node accessibilityAttributeValue:NSAccessibilityValueAttribute];
+  EXPECT_NSEQ(kTestStringValue, value);
+
+  // Write a new NSAccessibilityValueAttribute.
+  EXPECT_TRUE(
+      [ax_node accessibilityIsAttributeSettable:NSAccessibilityValueAttribute]);
+  [ax_node accessibilitySetValue:kTestPlaceholderText
+                    forAttribute:NSAccessibilityValueAttribute];
+  EXPECT_NSEQ(kTestPlaceholderText,
+              AttributeValueAtMidpoint(NSAccessibilityValueAttribute));
+  EXPECT_EQ(base::SysNSStringToUTF16(kTestPlaceholderText), textfield->text());
+
+  // Test a read-only textfield.
+  textfield->SetReadOnly(true);
+  EXPECT_FALSE(
+      [ax_node accessibilityIsAttributeSettable:NSAccessibilityValueAttribute]);
+  [ax_node accessibilitySetValue:kTestStringValue
+                    forAttribute:NSAccessibilityValueAttribute];
+  EXPECT_NSEQ(kTestPlaceholderText,
+              AttributeValueAtMidpoint(NSAccessibilityValueAttribute));
+  EXPECT_EQ(base::SysNSStringToUTF16(kTestPlaceholderText), textfield->text());
+}
+
 }  // namespace views