Bug 1794657 - Part 2: Remove the main-thread-only host map from ExtensionPolicyService, r=kmag

We're still holding strong references to the WebExtensionPolicy objects through
the `mExtensions` map, so we don't need to worry about the policy instances
dying earlier after this change.

Differential Revision: https://phabricator.services.mozilla.com/D159087

toolkit/components/extensions/ExtensionPolicyService.cpp

@@ -155,6 +155,13 @@ WebExtensionPolicy* ExtensionPolicyService::GetByURL(const URLInfo& aURL) {
   return nullptr;
 }
 
+WebExtensionPolicy* ExtensionPolicyService::GetByHost(
+    const nsACString& aHost) const {
+  AssertIsOnMainThread();
+  RefPtr<WebExtensionPolicyCore> core = GetCoreByHost(aHost);
+  return core ? core->GetMainThreadPolicy() : nullptr;
+}
+
 void ExtensionPolicyService::GetAll(
     nsTArray<RefPtr<WebExtensionPolicy>>& aResult) {
   AppendToArray(aResult, mExtensions.Values());
@@ -170,8 +177,6 @@ bool ExtensionPolicyService::RegisterExtension(WebExtensionPolicy& aPolicy) {
   }
 
   mExtensions.InsertOrUpdate(aPolicy.Id(), RefPtr{&aPolicy});
-  mExtensionHosts.InsertOrUpdate(aPolicy.MozExtensionHostname(),
-                                 RefPtr{&aPolicy});
 
   {
     StaticAutoWriteLock lock(sCoreByHostLock);
@@ -190,7 +195,6 @@ bool ExtensionPolicyService::UnregisterExtension(WebExtensionPolicy& aPolicy) {
   }
 
   mExtensions.Remove(aPolicy.Id());
-  mExtensionHosts.Remove(aPolicy.MozExtensionHostname());
 
   {
     StaticAutoWriteLock lock(sCoreByHostLock);
@@ -665,8 +669,7 @@ nsresult ExtensionPolicyService::ExtensionURIToAddonId(nsIURI* aURI,
   return NS_OK;
 }
 
-NS_IMPL_CYCLE_COLLECTION(ExtensionPolicyService, mExtensions, mExtensionHosts,
-                         mObservers)
+NS_IMPL_CYCLE_COLLECTION(ExtensionPolicyService, mExtensions, mObservers)
 
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ExtensionPolicyService)
   NS_INTERFACE_MAP_ENTRY(nsIAddonPolicyService)

toolkit/components/extensions/ExtensionPolicyService.h

@@ -77,11 +77,7 @@ class ExtensionPolicyService final : public nsIAddonPolicyService,
 
   WebExtensionPolicy* GetByURL(const extensions::URLInfo& aURL);
 
-  WebExtensionPolicy* GetByHost(const nsACString& aHost) const {
-    nsAutoCString host;
-    ToLowerCase(aHost, host);
-    return mExtensionHosts.GetWeak(host);
-  }
+  WebExtensionPolicy* GetByHost(const nsACString& aHost) const;
 
   void GetAll(nsTArray<RefPtr<WebExtensionPolicy>>& aResult);
 
@@ -119,7 +115,6 @@ class ExtensionPolicyService final : public nsIAddonPolicyService,
       const nsTArray<RefPtr<extensions::WebExtensionContentScript>>& aScripts);
 
   nsRefPtrHashtable<nsPtrHashKey<const nsAtom>, WebExtensionPolicy> mExtensions;
-  nsRefPtrHashtable<nsCStringHashKey, WebExtensionPolicy> mExtensionHosts;
 
   nsRefPtrHashtable<nsPtrHashKey<const extensions::DocumentObserver>,
                     extensions::DocumentObserver>