Implement MSAA/IA2 HelpText property

This change implements HelpText property for views by exposing
one of the following:
1. If Placeholder is available, set its value as the HelpText.
2. If the element has NameFrom::kTitle or NameFrom::kPlaceholder,
expose StringAttribute::kName as the HelpText.
3. If Tooltip is available, set its value as the HelpText.
4. Return S_FALSE if there is no help information available.

This change also adds an AXPlatformNodeWinTest to test
the new implementation of HelpText property.

Change-Id: I8a3d0d38273da75d7969a60f70a4627c96e8ffde
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1661003
Reviewed-by: Kevin Babbitt <kbabbitt@microsoft.com>
Commit-Queue: Maria Villarreal <mavill@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#670267}

ui/accessibility/platform/ax_platform_node_win.cc

@@ -1064,8 +1064,9 @@ IFACEMETHODIMP AXPlatformNodeWin::get_accState(VARIANT var_id, VARIANT* state) {
 
 IFACEMETHODIMP AXPlatformNodeWin::get_accHelp(VARIANT var_id, BSTR* help) {
   WIN_ACCESSIBILITY_API_HISTOGRAM(UMA_API_GET_ACC_HELP);
-  COM_OBJECT_VALIDATE_1_ARG(help);
-  return S_FALSE;
+  AXPlatformNodeWin* target;
+  COM_OBJECT_VALIDATE_VAR_ID_1_ARG_AND_GET_TARGET(var_id, help, target);
+  return target->GetHelpText(help);
 }
 
 IFACEMETHODIMP AXPlatformNodeWin::get_accValue(VARIANT var_id, BSTR* value) {
@@ -3766,20 +3767,8 @@ IFACEMETHODIMP AXPlatformNodeWin::GetPropertyValue(PROPERTYID property_id,
       break;
 
     case UIA_HelpTextPropertyId:
-      if (HasStringAttribute(ax::mojom::StringAttribute::kPlaceholder)) {
-        V_VT(result) = VT_BSTR;
-        GetStringAttributeAsBstr(ax::mojom::StringAttribute::kPlaceholder,
-                                 &V_BSTR(result));
-      } else if (data.GetNameFrom() == ax::mojom::NameFrom::kPlaceholder ||
-                 data.GetNameFrom() == ax::mojom::NameFrom::kTitle) {
-        V_VT(result) = VT_BSTR;
-        GetStringAttributeAsBstr(ax::mojom::StringAttribute::kName,
-                                 &V_BSTR(result));
-      } else if (HasStringAttribute(ax::mojom::StringAttribute::kTooltip)) {
-        V_VT(result) = VT_BSTR;
-        GetStringAttributeAsBstr(ax::mojom::StringAttribute::kTooltip,
-                                 &V_BSTR(result));
-      }
+      V_VT(result) = VT_BSTR;
+      GetHelpText(&V_BSTR(result));
       break;
 
     case UIA_IsContentElementPropertyId:
@@ -6815,6 +6804,21 @@ HRESULT AXPlatformNodeWin::AllocateComArrayFromVector(
   return S_OK;
 }
 
+HRESULT AXPlatformNodeWin::GetHelpText(BSTR* helpText) {
+  if (HasStringAttribute(ax::mojom::StringAttribute::kPlaceholder)) {
+    return GetStringAttributeAsBstr(ax::mojom::StringAttribute::kPlaceholder,
+                                    helpText);
+  } else if (GetData().GetNameFrom() == ax::mojom::NameFrom::kPlaceholder ||
+             GetData().GetNameFrom() == ax::mojom::NameFrom::kTitle) {
+    return GetStringAttributeAsBstr(ax::mojom::StringAttribute::kName,
+                                    helpText);
+  } else if (HasStringAttribute(ax::mojom::StringAttribute::kTooltip)) {
+    return GetStringAttributeAsBstr(ax::mojom::StringAttribute::kTooltip,
+                                    helpText);
+  }
+  return S_FALSE;
+}
+
 // TODO(dmazzoni): Remove this function once combo box refactoring is
 // complete.
 bool AXPlatformNodeWin::IsAncestorComboBox() {

ui/accessibility/platform/ax_platform_node_win.h

@@ -1201,6 +1201,9 @@ class AX_EXPORT __declspec(uuid("26f5641a-246d-457b-a96d-07f3fae6acf2"))
   // Helper method for mutating the ISelectionItemProvider selected state
   HRESULT ISelectionItemProviderSetSelected(bool selected);
 
+  // Helper method for getting the help text property.
+  HRESULT GetHelpText(BSTR* helpText);
+
   //
   // Getters for UIA GetTextAttributeValue
   //

ui/accessibility/platform/ax_platform_node_win_unittest.cc

@@ -523,6 +523,101 @@ TEST_F(AXPlatformNodeWinTest, TestIAccessibleShortcut) {
             root_obj->get_accKeyboardShortcut(bad_id, k2.Receive()));
 }
 
+TEST_F(AXPlatformNodeWinTest, TestIAccessibleHelpText) {
+  AXNodeData root;
+  root.id = 0;
+
+  // Test Placeholder StringAttribute is exposed.
+  AXNodeData node1;
+  node1.id = 1;
+  node1.SetName("name-from-title");
+  node1.AddIntAttribute(ax::mojom::IntAttribute::kNameFrom,
+                        static_cast<int>(ax::mojom::NameFrom::kTitle));
+  node1.AddStringAttribute(ax::mojom::StringAttribute::kPlaceholder,
+                           "placeholder");
+  root.child_ids.push_back(node1.id);
+
+  // Test NameFrom Title is exposed.
+  AXNodeData node2;
+  node2.id = 2;
+  node2.SetName("name-from-title");
+  node2.AddIntAttribute(ax::mojom::IntAttribute::kNameFrom,
+                        static_cast<int>(ax::mojom::NameFrom::kTitle));
+  root.child_ids.push_back(node2.id);
+
+  // Test NameFrom Placeholder is exposed.
+  AXNodeData node3;
+  node3.id = 3;
+  node3.SetName("name-from-placeholder");
+  node3.AddIntAttribute(ax::mojom::IntAttribute::kNameFrom,
+                        static_cast<int>(ax::mojom::NameFrom::kPlaceholder));
+  root.child_ids.push_back(node3.id);
+
+  // Test Tooltip StringAttribute is exposed.
+  AXNodeData node4;
+  node4.id = 4;
+  node4.SetName("name-from-attribute");
+  node4.AddIntAttribute(ax::mojom::IntAttribute::kNameFrom,
+                        static_cast<int>(ax::mojom::NameFrom::kAttribute));
+  node4.AddStringAttribute(ax::mojom::StringAttribute::kTooltip, "tooltip");
+  root.child_ids.push_back(node4.id);
+
+  // Test StringAttribute is not exposed without explicit
+  // Placeholder / Title / Tooltip.
+  AXNodeData node5;
+  node5.id = 5;
+  node5.SetName("name-from-attribute");
+  node5.AddIntAttribute(ax::mojom::IntAttribute::kNameFrom,
+                        static_cast<int>(ax::mojom::NameFrom::kAttribute));
+  root.child_ids.push_back(node5.id);
+
+  Init(root, node1, node2, node3, node4, node5);
+
+  auto* root_node = GetRootNode();
+
+  ScopedBstr helpText1;
+  ComPtr<IAccessible> child_node1(
+      IAccessibleFromNode(root_node->children()[0]));
+  EXPECT_EQ(S_OK, child_node1->get_accHelp(SELF, helpText1.Receive()));
+  EXPECT_STREQ(L"placeholder", helpText1);
+
+  ScopedBstr helpText2;
+  ComPtr<IAccessible> child_node2(
+      IAccessibleFromNode(root_node->children()[1]));
+  EXPECT_EQ(S_OK, child_node2->get_accHelp(SELF, helpText2.Receive()));
+  EXPECT_STREQ(L"name-from-title", helpText2);
+
+  ScopedBstr helpText3;
+  ComPtr<IAccessible> child_node3(
+      IAccessibleFromNode(root_node->children()[2]));
+  EXPECT_EQ(S_OK, child_node3->get_accHelp(SELF, helpText3.Receive()));
+  EXPECT_STREQ(L"name-from-placeholder", helpText3);
+
+  ScopedBstr helpText4;
+  ComPtr<IAccessible> child_node4(
+      IAccessibleFromNode(root_node->children()[3]));
+  EXPECT_EQ(S_OK, child_node4->get_accHelp(SELF, helpText4.Receive()));
+  EXPECT_STREQ(L"tooltip", helpText4);
+
+  ScopedBstr helpText5;
+  ComPtr<IAccessible> child_node5(
+      IAccessibleFromNode(root_node->children()[4]));
+  EXPECT_EQ(S_FALSE, child_node5->get_accHelp(SELF, helpText5.Receive()));
+
+  ScopedBstr helpText6;
+  ScopedVariant root_id(0);
+  EXPECT_EQ(S_OK, child_node4->get_accHelp(root_id, helpText6.Receive()));
+  EXPECT_STREQ(L"tooltip", helpText6);
+
+  EXPECT_EQ(E_INVALIDARG, child_node5->get_accHelp(SELF, nullptr));
+  ScopedVariant var_id(5);
+  EXPECT_EQ(E_INVALIDARG,
+            child_node5->get_accHelp(var_id, helpText5.Receive()));
+  ScopedVariant bad_id(999);
+  EXPECT_EQ(E_INVALIDARG,
+            child_node5->get_accHelp(bad_id, helpText5.Receive()));
+}
+
 TEST_F(AXPlatformNodeWinTest,
        TestIAccessibleSelectionListBoxOptionNothingSelected) {
   AXNodeData list;