Switch to mojo localstorage backend by default.

content/browser/dom_storage/local_storage_context_mojo.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/dom_storage/local_storage_context_mojo.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 370 matching lines @@
     // Queue this OpenLocalStorage call for when we have a level db pointer.
     on_database_opened_callbacks_.push_back(std::move(callback));
     return;
   }
 
   std::move(callback).Run();
 }
 
 void LocalStorageContextMojo::InitiateConnection(bool in_memory_only) {
   DCHECK_EQ(connection_state_, CONNECTION_IN_PROGRESS);
-  CHECK(connector_);
+
+  // Unit tests might not always have a Connector, use in-memory only if that
+  // happens.
+  if (!connector_) {
+    OnDatabaseOpened(false, leveldb::mojom::DatabaseError::OK);
+    return;
+  }
+
   if (!subdirectory_.empty() && !in_memory_only) {
     // We were given a subdirectory to write to. Get it and use a disk backed
     // database.
     connector_->BindInterface(file::mojom::kServiceName, &file_system_);
     file_system_->GetSubDirectory(
         subdirectory_.AsUTF8Unsafe(), MakeRequest(&directory_),
         base::Bind(&LocalStorageContextMojo::OnDirectoryOpened,
                    weak_ptr_factory_.GetWeakPtr()));
   } else {
     // We were not given a subdirectory. Use a memory backed database.
@@ skipping 198 matching lines @@
     return found->second->level_db_wrapper();
 
   auto holder = base::MakeUnique<LevelDBWrapperHolder>(this, origin);
   LevelDBWrapperImpl* wrapper_ptr = holder->level_db_wrapper();
   level_db_wrappers_[origin] = std::move(holder);
   return wrapper_ptr;
 }
 
 void LocalStorageContextMojo::RetrieveStorageUsage(
     GetStorageUsageCallback callback) {
+  if (!database_) {
+    // If for whatever reason no leveldb database is available, no storage is
+    // used, so return an empty array.
+    std::move(callback).Run(std::vector<LocalStorageUsageInfo>());
+    return;
+  }
+
   database_->GetPrefixed(
       std::vector<uint8_t>(kMetaPrefix, kMetaPrefix + arraysize(kMetaPrefix)),
       base::Bind(&LocalStorageContextMojo::OnGotMetaData,
                  weak_ptr_factory_.GetWeakPtr(), base::Passed(&callback)));
 }
 
 void LocalStorageContextMojo::OnGotMetaData(
     GetStorageUsageCallback callback,
     leveldb::mojom::DatabaseError status,
     std::vector<leveldb::mojom::KeyValuePtr> data) {
@@ skipping 52 matching lines @@
     OnShutdownComplete(leveldb::mojom::DatabaseError::OK);
   }
 }
 
 void LocalStorageContextMojo::OnShutdownComplete(
     leveldb::mojom::DatabaseError error) {
   delete this;
 }
 
 }  // namespace content