IndexedDB: Eliminate some reference churn in IndexedDBContextImpl.

While here, this CL also marks some IndexedDBContextImpl data members
const. No functional changes are introduced.

Change-Id: I45d4b887d6a9fcf6a3719cc32e745837594dd4e0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2609904Reviewed-by: enne <enne@chromium.org>
Commit-Queue: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#840445}

content/browser/indexed_db/indexed_db_context_impl.cc

@@ -138,11 +138,11 @@ IndexedDBContextImpl::IndexedDBContextImpl(
       data_path_(data_path.empty() ? base::FilePath()
                                    : data_path.Append(kIndexedDBDirectory)),
       force_keep_session_state_(false),
-      quota_manager_proxy_(quota_manager_proxy),
+      quota_manager_proxy_(std::move(quota_manager_proxy)),
       clock_(clock),
       filesystem_proxy_(storage::CreateFilesystemProxy()) {
   IDB_TRACE("init");
-  quota_manager_proxy->RegisterClient(
+  quota_manager_proxy_->RegisterClient(
       base::MakeRefCounted<IndexedDBQuotaClient>(this),
       storage::QuotaClientType::kIndexedDatabase,
       {blink::mojom::StorageType::kTemporary});

content/browser/indexed_db/indexed_db_context_impl.h

@@ -232,7 +232,7 @@ class CONTENT_EXPORT IndexedDBContextImpl
   // backing stores); the cache will be primed as needed by checking disk.
   std::set<url::Origin>* GetOriginSet();
 
-  scoped_refptr<base::SequencedTaskRunner> idb_task_runner_;
+  const scoped_refptr<base::SequencedTaskRunner> idb_task_runner_;
   IndexedDBDispatcherHost dispatcher_host_;
 
   // Bound and accessed on the |idb_task_runner_|.
@@ -247,20 +247,20 @@ class CONTENT_EXPORT IndexedDBContextImpl
 
   // If true, nothing (not even session-only data) should be deleted on exit.
   bool force_keep_session_state_;
-  scoped_refptr<storage::SpecialStoragePolicy> special_storage_policy_;
-  scoped_refptr<storage::QuotaManagerProxy> quota_manager_proxy_;
+  const scoped_refptr<storage::SpecialStoragePolicy> special_storage_policy_;
+  const scoped_refptr<storage::QuotaManagerProxy> quota_manager_proxy_;
   std::unique_ptr<std::set<url::Origin>> origin_set_;
   std::map<url::Origin, int64_t> origin_size_map_;
   // The set of origins whose storage should be cleared on shutdown.
   std::set<url::Origin> origins_to_purge_on_shutdown_;
-  base::Clock* clock_;
+  base::Clock* const clock_;
 
   mojo::ReceiverSet<storage::mojom::IndexedDBControl> receivers_;
   mojo::ReceiverSet<storage::mojom::IndexedDBControlTest> test_receivers_;
   base::Optional<mojo::Receiver<storage::mojom::MockFailureInjector>>
       mock_failure_injector_;
   mojo::RemoteSet<storage::mojom::IndexedDBObserver> observers_;
-  std::unique_ptr<storage::FilesystemProxy> filesystem_proxy_;
+  const std::unique_ptr<storage::FilesystemProxy> filesystem_proxy_;
 
   DISALLOW_COPY_AND_ASSIGN(IndexedDBContextImpl);
 };