Bug 1794974: Part 6: Add xpcAccessibilityService::setCacheDomains, r=Jamie

This revision implements a simple way to set cache domains from XPCOM, which is
crucial for testing caching granularity.

Differential Revision: https://phabricator.services.mozilla.com/D220040

Author: Nathan LaPre

accessible/interfaces/nsIAccessibilityService.idl

@@ -78,6 +78,15 @@ interface nsIAccessibilityService : nsISupports
    */
   nsIAccessible getAccessibleFromCache(in Node aNode);
 
+  /**
+   * Set the active cache domains. If any given domains are not currently
+   * active, then the accessibility service will enable them in all content
+   * processes, causing them to be cached.
+   *
+   * @param aCacheDomains [in] the cache domains to set
+   */
+  void setCacheDomains(in unsigned long long aCacheDomains);
+
   /**
    * Create a new pivot for tracking a position and traversing a subtree.
    *

accessible/xpcom/xpcAccessibilityService.cpp

@@ -229,6 +229,17 @@ xpcAccessibilityService::GetAccessibleFromCache(nsINode* aNode,
   return NS_OK;
 }
 
+NS_IMETHODIMP
+xpcAccessibilityService::SetCacheDomains(uint64_t aCacheDomains) {
+  nsAccessibilityService* accService = GetAccService();
+  if (!accService) {
+    return NS_ERROR_SERVICE_NOT_AVAILABLE;
+  }
+
+  accService->SetCacheDomains(aCacheDomains);
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 xpcAccessibilityService::CreateAccessiblePivot(nsIAccessible* aRoot,
                                                nsIAccessiblePivot** aPivot) {