Comment ListenToCookieChanges call in StoragePartitionImplMap::Get.

This adds a comment before the CookieStoreContext::ListenToCookieChanges
call, and renames one of its parameters to hopefully make it clearer.
If anyone else ever misreads the code the way I did, hopefully this
change will help explain things.

Change-Id: Id5256b85c179f9a16a2c5b0df18288bb3122e245
Reviewed-on: https://chromium-review.googlesource.com/c/1413890Reviewed-by: Victor Costan <pwnall@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: Robbie McElrath <rmcelrath@chromium.org>
Cr-Commit-Position: refs/heads/master@{#623156}

content/browser/cookie_store/cookie_store_context.cc

@@ -25,7 +25,7 @@ CookieStoreContext::~CookieStoreContext() {
 
 void CookieStoreContext::Initialize(
     scoped_refptr<ServiceWorkerContextWrapper> service_worker_context,
-    base::OnceCallback<void(bool)> callback) {
+    base::OnceCallback<void(bool)> success_callback) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
 #if DCHECK_IS_ON()
   DCHECK(!initialize_called_) << __func__ << " called twice";
@@ -43,12 +43,13 @@ void CookieStoreContext::Initialize(
                 task_runner->PostTask(
                     FROM_HERE, base::BindOnce(std::move(callback), result));
               },
-              base::SequencedTaskRunnerHandle::Get(), std::move(callback))));
+              base::SequencedTaskRunnerHandle::Get(),
+              std::move(success_callback))));
 }
 
 void CookieStoreContext::ListenToCookieChanges(
     ::network::mojom::NetworkContext* network_context,
-    base::OnceCallback<void(bool)> callback) {
+    base::OnceCallback<void(bool)> success_callback) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
 #if DCHECK_IS_ON()
   DCHECK(initialize_called_) << __func__ << " called before Initialize()";
@@ -69,7 +70,8 @@ void CookieStoreContext::ListenToCookieChanges(
                 task_runner->PostTask(
                     FROM_HERE, base::BindOnce(std::move(callback), result));
               },
-              base::SequencedTaskRunnerHandle::Get(), std::move(callback))));
+              base::SequencedTaskRunnerHandle::Get(),
+              std::move(success_callback))));
 }
 
 void CookieStoreContext::CreateService(blink::mojom::CookieStoreRequest request,
@@ -87,24 +89,24 @@ void CookieStoreContext::CreateService(blink::mojom::CookieStoreRequest request,
 
 void CookieStoreContext::InitializeOnIOThread(
     scoped_refptr<ServiceWorkerContextWrapper> service_worker_context,
-    base::OnceCallback<void(bool)> callback) {
+    base::OnceCallback<void(bool)> success_callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DCHECK(!cookie_store_manager_) << __func__ << " called more than once";
 
   cookie_store_manager_ =
       std::make_unique<CookieStoreManager>(std::move(service_worker_context));
-  cookie_store_manager_->LoadAllSubscriptions(std::move(callback));
+  cookie_store_manager_->LoadAllSubscriptions(std::move(success_callback));
 }
 
 void CookieStoreContext::ListenToCookieChangesOnIOThread(
     ::network::mojom::CookieManagerPtrInfo cookie_manager_ptr_info,
-    base::OnceCallback<void(bool)> callback) {
+    base::OnceCallback<void(bool)> success_callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DCHECK(cookie_store_manager_);
 
   cookie_store_manager_->ListenToCookieChanges(
       ::network::mojom::CookieManagerPtr(std::move(cookie_manager_ptr_info)),
-      std::move(callback));
+      std::move(success_callback));
 }
 
 void CookieStoreContext::CreateServiceOnIOThread(

content/browser/cookie_store/cookie_store_context.h

@@ -52,13 +52,13 @@ class CONTENT_EXPORT CookieStoreContext
   // errors.
   void Initialize(
       scoped_refptr<ServiceWorkerContextWrapper> service_worker_context,
-      base::OnceCallback<void(bool)> callback);
+      base::OnceCallback<void(bool)> success_callback);
 
   // Starts listening to cookie changes from a network service instance.
   //
   // The callback is called with the (success / failure) result of subscribing.
   void ListenToCookieChanges(::network::mojom::NetworkContext* network_context,
-                             base::OnceCallback<void(bool)> callback);
+                             base::OnceCallback<void(bool)> success_callback);
 
   // Routes a mojo request to the CookieStoreManager on the IO thread.
   void CreateService(blink::mojom::CookieStoreRequest request,
@@ -71,11 +71,11 @@ class CONTENT_EXPORT CookieStoreContext
 
   void InitializeOnIOThread(
       scoped_refptr<ServiceWorkerContextWrapper> service_worker_context,
-      base::OnceCallback<void(bool)> callback);
+      base::OnceCallback<void(bool)> success_callback);
 
   void ListenToCookieChangesOnIOThread(
       ::network::mojom::CookieManagerPtrInfo cookie_manager_ptr_info,
-      base::OnceCallback<void(bool)> callback);
+      base::OnceCallback<void(bool)> success_callback);
 
   void CreateServiceOnIOThread(blink::mojom::CookieStoreRequest request,
                                const url::Origin& origin);

content/browser/storage_partition_impl_map.cc

@@ -455,8 +455,9 @@ StoragePartitionImpl* StoragePartitionImplMap::Get(
                   partition->GetPath(), in_memory));
   }
 
+  // Arm the serviceworker cookie change observation API.
   partition->GetCookieStoreContext()->ListenToCookieChanges(
-      partition->GetNetworkContext(), base::DoNothing());
+      partition->GetNetworkContext(), /*success_callback=*/base::DoNothing());
 
   if (!base::FeatureList::IsEnabled(network::features::kNetworkService)) {
     // This needs to happen after SetURLRequestContext() since we need this