Bug 414656. Expose native enumerated role along with ARIA landmark roles. Patch by Alexander Surkov. r=aaronlev, a=schrep

accessible/src/base/nsARIAMap.cpp

@@ -213,6 +213,15 @@ nsRoleMapEntry nsARIAMap::gLandmarkRoleMap = {
   kEndEntry
 };
 
+nsRoleMapEntry nsARIAMap::gEmptyRoleMap = {
+  "",
+  nsIAccessibleRole::ROLE_NOTHING,
+  eNameLabelOrTitle,
+  eNoValue,
+  kNoReqStates,
+  kEndEntry
+};
+
 /**
  * Universal states:
  * The following state rules are applied to any accessible element,

accessible/src/base/nsARIAMap.h

@@ -125,9 +125,29 @@ struct nsRoleMapEntry
  */
 struct nsARIAMap
 {
+  /**
+   * Array of supported ARIA role map entries and its length.
+   */
   static nsRoleMapEntry gWAIRoleMap[];
   static PRUint32 gWAIRoleMapLength;
+
+  /**
+   * Landmark role map entry. Used when specified ARIA role isn't mapped to
+   * accessibility API.
+   */
   static nsRoleMapEntry gLandmarkRoleMap;
+
+  /**
+   * Empty role map entry. Used by accessibility service to create an accessible
+   * if the accessible can't use role of used accessible class. For example,
+   * it is used for table cells that aren't contained by table.
+   */
+  static nsRoleMapEntry gEmptyRoleMap;
+
+  /**
+   * State map of ARIA states applied to any accessible not depending on
+   * the role.
+   */
   static nsStateMapEntry gWAIUnivStateMap[];
 };
 

accessible/src/base/nsAccessibilityService.cpp

@@ -1450,7 +1450,8 @@ NS_IMETHODIMP nsAccessibilityService::GetAccessible(nsIDOMNode *aNode,
           }
           if (tableAccessible && nsAccessible::Role(tableAccessible) != nsIAccessibleRole::ROLE_TABLE) {
             NS_ASSERTION(!roleMapEntry, "Should not be changing ARIA role, just overriding impl class role");
-            roleMapEntry = &nsARIAMap::gLandmarkRoleMap; // Not in table: override role (roleMap entry was null)
+            // Not in table: override role (roleMap entry was null).
+            roleMapEntry = &nsARIAMap::gEmptyRoleMap;
           }
           break;
         }
@@ -1458,7 +1459,8 @@ NS_IMETHODIMP nsAccessibilityService::GetAccessible(nsIDOMNode *aNode,
           // Stop before we are fooled by any additional table ancestors
           // This table cell frameis part of a separate ancestor table.
           NS_ASSERTION(!roleMapEntry, "Should not be changing ARIA role, just overriding impl class role");
-          roleMapEntry = &nsARIAMap::gLandmarkRoleMap; // Not in table: override role
+          // Not in table: override role (roleMap entry was null).
+          roleMapEntry = &nsARIAMap::gEmptyRoleMap;
           break;
         }
       }

accessible/src/base/nsAccessible.cpp

@@ -1987,10 +1987,13 @@ NS_IMETHODIMP nsAccessible::GetFinalRole(PRUint32 *aRole)
       }
     }
 
-    // We can now expose ROLE_NOTHING when there is a role map entry, which will
-    // cause ATK to use ROLE_UNKNOWN and MSAA to use a BSTR role with the ARIA role or element's tag.
-    // In either case the AT can also use the object attributes tag and xml-roles to find out more.
-    return NS_OK;
+    if (mRoleMapEntry == &nsARIAMap::gEmptyRoleMap) {
+      // We can now expose ROLE_NOTHING when there is a role map entry, which
+      // will cause ATK to use ROLE_UNKNOWN and MSAA to use a BSTR role with
+      // the ARIA role or element's tag. In either case the AT can also use
+      // the object attributes tag and xml-roles to find out more.
+      return NS_OK;
+    }
   }
   return mDOMNode ? GetRole(aRole) : NS_ERROR_FAILURE;  // Node already shut down
 }