MacViews/a11y: Allow accessibility clients to set new selections in Textfields.

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 3d641d190f9eab41fa0d4a97d726766736902263..d139084a655da33cd24e40fd0464110facb35053 100644
--- a/ui/views/widget/native_widget_mac_accessibility_unittest.mm
+++ b/ui/views/widget/native_widget_mac_accessibility_unittest.mm
@@ -411,6 +411,27 @@ TEST_F(NativeWidgetMacAccessibilityTest, TextfieldWritableAttributes) {
   // Make sure the cursor is at the end of the replacement.
   EXPECT_EQ(gfx::Range(front.length() + replacement.length()),
             textfield->GetSelectedRange());
+
+  EXPECT_TRUE([ax_node accessibilityIsAttributeSettable:
+                           NSAccessibilitySelectedTextRangeAttribute]);
+  // Check it's still possible to change the selection range when read-only.
+  textfield->SetReadOnly(true);
+  EXPECT_TRUE([ax_node accessibilityIsAttributeSettable:
+                           NSAccessibilitySelectedTextRangeAttribute]);
+
+  // Change the selection to a valid range within the text.
+  [ax_node accessibilitySetValue:[NSValue valueWithRange:NSMakeRange(2, 5)]
+                    forAttribute:NSAccessibilitySelectedTextRangeAttribute];
+  EXPECT_EQ(gfx::Range(2, 7), textfield->GetSelectedRange());
+  // If the length is longer than the value length, default to the max possible.
+  [ax_node accessibilitySetValue:[NSValue valueWithRange:NSMakeRange(0, 1000)]
+                    forAttribute:NSAccessibilitySelectedTextRangeAttribute];
+  EXPECT_EQ(gfx::Range(0, textfield->text().length()),
+            textfield->GetSelectedRange());
+  // Check just moving the cursor works, too.
+  [ax_node accessibilitySetValue:[NSValue valueWithRange:NSMakeRange(5, 0)]
+                    forAttribute:NSAccessibilitySelectedTextRangeAttribute];
+  EXPECT_EQ(gfx::Range(5, 5), textfield->GetSelectedRange());
 }
 
 }  // namespace views