Bug 1322235: Part 7 - DeCOMtaminate moz-extension protocol handler. r=billm

This removes unnecessary COM overhead from the extension protocol service,
particularly from the flag lookup code, which is called often, and from hot
paths. The devirtualized lookups should have virtually no overhead for
extensions without web-accessible resources, and very little overhead except
when resources are specified as non-prefix globs.

MozReview-Commit-ID: 4hQ7GuQSjvW

--HG--
extra : rebase_source : 61897a204abd915ad61852fa475cde2de51753f3

netwerk/protocol/res/ExtensionProtocolHandler.cpp

@@ -6,7 +6,7 @@
 
 #include "ExtensionProtocolHandler.h"
 
-#include "nsIAddonPolicyService.h"
+#include "mozilla/ExtensionPolicyService.h"
 #include "nsServiceManagerUtils.h"
 #include "nsIURL.h"
 #include "nsIChannel.h"
@@ -21,22 +21,30 @@
 namespace mozilla {
 namespace net {
 
+using extensions::URLInfo;
+
 NS_IMPL_QUERY_INTERFACE(ExtensionProtocolHandler, nsISubstitutingProtocolHandler,
                         nsIProtocolHandler, nsIProtocolHandlerWithDynamicFlags,
                         nsISupportsWeakReference)
 NS_IMPL_ADDREF_INHERITED(ExtensionProtocolHandler, SubstitutingProtocolHandler)
 NS_IMPL_RELEASE_INHERITED(ExtensionProtocolHandler, SubstitutingProtocolHandler)
 
+static inline ExtensionPolicyService&
+EPS()
+{
+  return ExtensionPolicyService::GetSingleton();
+}
+
 nsresult
 ExtensionProtocolHandler::GetFlagsForURI(nsIURI* aURI, uint32_t* aFlags)
 {
   // In general a moz-extension URI is only loadable by chrome, but a whitelisted
   // subset are web-accessible (and cross-origin fetchable). Check that whitelist.
-  nsCOMPtr<nsIAddonPolicyService> aps = do_GetService("@mozilla.org/addons/policy-service;1");
   bool loadableByAnyone = false;
-  if (aps) {
-    nsresult rv = aps->ExtensionURILoadableByAnyone(aURI, &loadableByAnyone);
-    NS_ENSURE_SUCCESS(rv, rv);
+
+  URLInfo url(aURI);
+  if (auto* policy = EPS().GetByURL(url)) {
+    loadableByAnyone = policy->IsPathWebAccessible(url.FilePath());
   }
 
   *aFlags = URI_STD | URI_IS_LOCAL_RESOURCE | (loadableByAnyone ? (URI_LOADABLE_BY_ANYONE | URI_FETCHABLE_BY_ANYONE) : URI_DANGEROUS_TO_LOAD);
@@ -55,22 +63,15 @@ ExtensionProtocolHandler::ResolveSpecialCases(const nsACString& aHost,
   if (!SubstitutingProtocolHandler::HasSubstitution(aHost)) {
     return false;
   }
+
   if (aPathname.EqualsLiteral("/_blank.html")) {
     aResult.AssignLiteral("about:blank");
     return true;
   }
+
   if (aPathname.EqualsLiteral("/_generated_background_page.html")) {
-    nsCOMPtr<nsIAddonPolicyService> aps =
-      do_GetService("@mozilla.org/addons/policy-service;1");
-    if (!aps) {
-      return false;
-    }
-    nsresult rv = aps->GetGeneratedBackgroundPageUrl(aHost, aResult);
-    NS_ENSURE_SUCCESS(rv, false);
-    if (!aResult.IsEmpty()) {
-      MOZ_RELEASE_ASSERT(Substring(aResult, 0, 5).Equals("data:"));
-      return true;
-    }
+    Unused << EPS().GetGeneratedBackgroundPageUrl(aHost, aResult);
+    return !aResult.IsEmpty();
   }
 
   return false;