NativeIO: NativeIOManager owns NativeIOQuotaClient.

This CL takes advantage of the fact that NativeIOQuotaClient is now
mojofied and no longer ref-counted, and simpifies NativeIO's ownership
graph.

Bug: 1016065
Change-Id: I6eb6fa259111101e95459b5c0655261b0d7e43d6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2644638Reviewed-by: Jarryd Goodman <jarrydg@chromium.org>
Commit-Queue: Victor Costan <pwnall@chromium.org>
Auto-Submit: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#846323}

content/browser/native_io/native_io_manager.cc

@@ -36,14 +36,13 @@ NativeIOManager::NativeIOManager(
     scoped_refptr<storage::QuotaManagerProxy> quota_manager_proxy)
     : root_path_(GetNativeIORootPath(profile_root)),
       special_storage_policy_(std::move(special_storage_policy)),
-      quota_manager_proxy_(std::move(quota_manager_proxy)) {
-  if (quota_manager_proxy) {
+      quota_manager_proxy_(std::move(quota_manager_proxy)),
+      quota_client_receiver_(&quota_client_) {
+  if (quota_manager_proxy_) {
     // Quota client assumes all backends have registered.
-    mojo::PendingRemote<storage::mojom::QuotaClient> quota_client;
-    mojo::MakeSelfOwnedReceiver(std::make_unique<NativeIOQuotaClient>(),
-                                quota_client.InitWithNewPipeAndPassReceiver());
-    quota_manager_proxy->RegisterClient(
-        std::move(quota_client), storage::QuotaClientType::kNativeIO,
+    quota_manager_proxy_->RegisterClient(
+        quota_client_receiver_.BindNewPipeAndPassRemote(),
+        storage::QuotaClientType::kNativeIO,
         {blink::mojom::StorageType::kTemporary});
   }
 }

content/browser/native_io/native_io_manager.h

@@ -11,8 +11,11 @@
 #include "base/files/file.h"
 #include "base/files/file_path.h"
 #include "base/sequence_checker.h"
+#include "components/services/storage/public/mojom/quota_client.mojom-forward.h"
+#include "content/browser/native_io/native_io_quota_client.h"
 #include "content/common/content_export.h"
 #include "mojo/public/cpp/bindings/pending_receiver.h"
+#include "mojo/public/cpp/bindings/receiver.h"
 #include "storage/browser/quota/quota_manager_proxy.h"
 #include "storage/browser/quota/special_storage_policy.h"
 #include "third_party/blink/public/mojom/native_io/native_io.mojom-forward.h"
@@ -72,6 +75,8 @@ class CONTENT_EXPORT NativeIOManager {
       std::string message = "");
 
  private:
+  SEQUENCE_CHECKER(sequence_checker_);
+
   std::map<url::Origin, std::unique_ptr<NativeIOHost>> hosts_;
 
   // Points to the root directory for NativeIO files.
@@ -84,7 +89,14 @@ class CONTENT_EXPORT NativeIOManager {
 
   const scoped_refptr<storage::QuotaManagerProxy> quota_manager_proxy_;
 
-  SEQUENCE_CHECKER(sequence_checker_);
+  NativeIOQuotaClient quota_client_;
+
+  // Once the QuotaClient receiver is destroyed, the underlying mojo connection
+  // is closed. Callbacks associated with mojo calls received over this
+  // connection may only be dropped after the connection is closed. For this
+  // reason, it's preferable to have the receiver be destroyed as early as
+  // possible during the NativeIOManager destruction process.
+  mojo::Receiver<storage::mojom::QuotaClient> quota_client_receiver_;
 };
 
 }  // namespace content

content/browser/native_io/native_io_manager_unittest.cc

@@ -177,6 +177,8 @@ class NativeIOManagerTest : public testing::Test {
   }
 
   void TearDown() override {
+    quota_manager_proxy()->SimulateQuotaManagerDestroyed();
+
     // Let the client go away before dropping a ref of the quota manager proxy.
     quota_manager_ = nullptr;
     quota_manager_proxy_ = nullptr;

content/browser/native_io/native_io_quota_client.cc

@@ -10,10 +10,7 @@
 
 namespace content {
 
-NativeIOQuotaClient::NativeIOQuotaClient() {
-  // Constructed on the UI thread and used on the IO thread.
-  DETACH_FROM_SEQUENCE(sequence_checker_);
-}
+NativeIOQuotaClient::NativeIOQuotaClient() = default;
 
 NativeIOQuotaClient::~NativeIOQuotaClient() {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

content/browser/native_io/native_io_quota_client.h

@@ -15,11 +15,10 @@
 namespace content {
 
 class NativeIOManager;
-enum class NativeIOOwner;
 
-// NativeIOQuotaClient is owned by the QuotaManager. There is one per
-// NativeIOManager/NativeIOOwner tuple. Created and accessed on
-// the IO thread.
+// Integrates NativeIO with the quota system.
+//
+// Each NativeIOManager owns exactly one NativeIOQuotaClient.
 class CONTENT_EXPORT NativeIOQuotaClient : public storage::mojom::QuotaClient {
  public:
   NativeIOQuotaClient();