Fixes and tests for UIA table interfaces

- Fix ITableItemProvider implementation to retrieve column/row header
items from the containing table.
- Eliminate S_FALSE return from ITableItemProvider methods.
- Return empty SAFEARRAYs as nullptr across all properties and control
patterns. This is the same behavior as EdgeHTML.
- Add missing tests for ITableItemProvider and update ITableProvider
tests to cover paths checking for invalid item references. To assist
with this, I split apart the SAFEARRAY testing macros to take either a
property ID or a SAFEARRAY directly.

Bug: 847971
Change-Id: If6f38d7ac7526fa374840f5755eb5aeb99a1b6d4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1601633
Commit-Queue: Kevin Babbitt <kbabbitt@microsoft.com>
Reviewed-by: Kurt Catti-Schmidt <kschmi@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#659147}

content/browser/accessibility/ax_platform_node_win_browsertest.cc

@@ -172,8 +172,14 @@ IN_PROC_BROWSER_TEST_F(AXPlatformNodeWinBrowserTest,
   LoadInitialAccessibilityTreeFromHtmlFilePath(
       "/accessibility/aria/aria-label.html");
 
-  UIAGetPropertyValueFlowsFromBrowserTestTemplate(
-      FindNode(ax::mojom::Role::kCheckBox, "aria label"), {});
+  base::win::ScopedVariant flows_from_variant;
+  ComPtr<IRawElementProviderSimple> node_provider =
+      QueryInterfaceFromNode<IRawElementProviderSimple>(
+          FindNode(ax::mojom::Role::kCheckBox, "aria label"));
+  node_provider->GetPropertyValue(UIA_FlowsFromPropertyId,
+                                  flows_from_variant.Receive());
+  ASSERT_EQ(VT_ARRAY | VT_UNKNOWN, flows_from_variant.type());
+  ASSERT_EQ(nullptr, V_ARRAY(flows_from_variant.ptr()));
 }
 
 IN_PROC_BROWSER_TEST_F(AXPlatformNodeWinBrowserTest,

ui/accessibility/platform/ax_platform_node_win.cc

@@ -399,6 +399,9 @@ SAFEARRAY* AXPlatformNodeWin::CreateUIAElementsArrayForReverseRelation(
 
 SAFEARRAY* AXPlatformNodeWin::CreateUIAElementsArrayFromIdVector(
     std::vector<int32_t>& ids) {
+  if (ids.size() == 0)
+    return nullptr;
+
   SAFEARRAY* uia_array = SafeArrayCreateVector(VT_UNKNOWN, 0, ids.size());
 
   LONG i = 0;
@@ -2080,12 +2083,10 @@ IFACEMETHODIMP AXPlatformNodeWin::GetColumnHeaderItems(SAFEARRAY** result) {
     return E_FAIL;
 
   std::vector<int32_t> column_header_ids =
-      GetDelegate()->GetColHeaderNodeIds(GetTableColumn());
+      GetTable()->GetDelegate()->GetColHeaderNodeIds(GetTableColumn());
   base::EraseIf(column_header_ids, [&](int32_t node_id) {
     return !IsValidUiaRelationTarget(GetDelegate()->GetFromNodeID(node_id));
   });
-  if (column_header_ids.empty())
-    return S_FALSE;
   *result = CreateUIAElementsArrayFromIdVector(column_header_ids);
   return S_OK;
 }
@@ -2098,12 +2099,10 @@ IFACEMETHODIMP AXPlatformNodeWin::GetRowHeaderItems(SAFEARRAY** result) {
     return E_FAIL;
 
   std::vector<int32_t> row_header_ids =
-      GetDelegate()->GetRowHeaderNodeIds(GetTableRow());
+      GetTable()->GetDelegate()->GetRowHeaderNodeIds(GetTableRow());
   base::EraseIf(row_header_ids, [&](int32_t node_id) {
     return !IsValidUiaRelationTarget(GetDelegate()->GetFromNodeID(node_id));
   });
-  if (row_header_ids.empty())
-    return S_FALSE;
   *result = CreateUIAElementsArrayFromIdVector(row_header_ids);
   return S_OK;
 }