Migrates legacy packaged app data when it's upgraded to a platform app

chrome/browser/extensions/app_data_migrator.cc

Index: chrome/browser/extensions/app_data_migrator.cc
diff --git a/chrome/browser/extensions/app_data_migrator.cc b/chrome/browser/extensions/app_data_migrator.cc
new file mode 100644
index 0000000000000000000000000000000000000000..6e19a329e1dfd8c1e1825a2adf3483a95b70b289
--- /dev/null
+++ b/chrome/browser/extensions/app_data_migrator.cc
@@ -0,0 +1,168 @@
+// Copyright 2014 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 "chrome/browser/extensions/app_data_migrator.h"
+
+#include "base/files/file_util.h"
+#include "chrome/browser/profiles/profile.h"
+#include "content/public/browser/browser_context.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/indexed_db_context.h"
+#include "content/public/browser/storage_partition.h"
+#include "extensions/browser/extension_registry.h"
+#include "extensions/common/extension.h"
+#include "storage/browser/fileapi/file_system_context.h"
+#include "storage/browser/fileapi/sandbox_file_system_backend_delegate.h"
+#include "storage/common/fileapi/file_system_types.h"
+
+using content::BrowserContext;
+using content::BrowserThread;
+using content::IndexedDBContext;
+using content::StoragePartition;
+using storage::FileSystemContext;
+using storage::SandboxFileSystemBackendDelegate;
+
+namespace {
+
+void MigrateOnFileSystemThread(FileSystemContext* old_fs_context,
+                               FileSystemContext* fs_context,
+                               const extensions::Extension* extension) {
+  DCHECK(
+      old_fs_context->default_file_task_runner()->RunsTasksOnCurrentThread());
+
+  SandboxFileSystemBackendDelegate* old_sandbox_delegate =
+      old_fs_context->sandbox_delegate();
+  SandboxFileSystemBackendDelegate* sandbox_delegate =
+      fs_context->sandbox_delegate();
+
+  GURL extension_url =
+      extensions::Extension::GetBaseURLFromExtensionId(extension->id());
+
+  scoped_ptr<storage::SandboxFileSystemBackendDelegate::OriginEnumerator>
+      enumerator(old_sandbox_delegate->CreateOriginEnumerator());
+
+  // Find out if there is a file system that needs migration.
+  GURL origin;
+  do {
+    origin = enumerator->Next();
+  } while (origin != extension_url && !origin.is_empty());
+
+  if (!origin.is_empty()) {
+    // Copy the temporary file system.
+    if (enumerator->HasFileSystemType(storage::kFileSystemTypeTemporary)) {
+      old_sandbox_delegate->CopyFileSystem(
+          extension_url, storage::kFileSystemTypeTemporary, sandbox_delegate);
+    }
+    // Copy the persistent file system.
+    if (enumerator->HasFileSystemType(storage::kFileSystemTypePersistent)) {
+      old_sandbox_delegate->CopyFileSystem(
+          extension_url, storage::kFileSystemTypePersistent, sandbox_delegate);
+    }
+  }
+}
+
+void MigrateOnIndexedDBThread(IndexedDBContext* old_indexed_db_context,
+                              IndexedDBContext* indexed_db_context,
+                              const extensions::Extension* extension) {
+  DCHECK(old_indexed_db_context->TaskRunner()->RunsTasksOnCurrentThread());
+
+  GURL extension_url =
+      extensions::Extension::GetBaseURLFromExtensionId(extension->id());
+
+  old_indexed_db_context->CopyOriginData(extension_url, indexed_db_context);
+}
+
+void MigrateFileSystem(StoragePartition* old_partition,
+                       StoragePartition* current_partition,
+                       const extensions::Extension* extension,
+                       const base::Closure& reply) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  // Retrieve the fs contexts in preparation for migration.
+  FileSystemContext* old_fs_context = old_partition->GetFileSystemContext();
+  FileSystemContext* fs_context = current_partition->GetFileSystemContext();
+
+  // Perform the file system migration on the old file system's
+  // sequenced task runner. This is to ensure it queues after any
+  // in-flight file system operations. After it completes, it should
+  // invoke the original callback passed into DoMigrationAndReply.
+  old_fs_context->default_file_task_runner()->PostTaskAndReply(
+      FROM_HERE,
+      base::Bind(&MigrateOnFileSystemThread, make_scoped_refptr(old_fs_context),
+                 make_scoped_refptr(fs_context), make_scoped_refptr(extension)),
+      reply);
+}
+
+void MigrateLegacyPartition(StoragePartition* old_partition,
+                            StoragePartition* current_partition,
+                            const extensions::Extension* extension,
+                            const base::Closure& reply) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  // Retrieve both IndexedDB contexts in preparation for migration.

[cmumford, 2015/01/06 15:30:26]

Nit: I'm not sure this context (and the one above) adds much.

+  IndexedDBContext* indexed_db_context =
+      current_partition->GetIndexedDBContext();
+  IndexedDBContext* old_indexed_db_context =
+      old_partition->GetIndexedDBContext();
+
+  // Create a closure for the file system migration. This is the next step in
+  // the migration flow after the IndexedDB migration.
+  base::Closure migrate_fs =
+      base::Bind(&MigrateFileSystem, old_partition, current_partition,

[tzik, 2015/01/16 05:56:36]

This closure may run after the profile has gone.

How about:
 - Convert this function to AppDataMigration's method,
 - Add an WeakPtrFactory to AppDataMigration.
 - Pass its WeakPtr as this pointer, so that the task will be canceled when the
instance is destroyed.

+                 make_scoped_refptr(extension), reply);
+
+  // Perform the IndexedDB migration on the old context's sequenced task
+  // runner. After completion, it should call MigrateFileSystem.
+  old_indexed_db_context->TaskRunner()->PostTaskAndReply(
+      FROM_HERE, base::Bind(&MigrateOnIndexedDBThread,
+                            make_scoped_refptr(old_indexed_db_context),
+                            make_scoped_refptr(indexed_db_context),
+                            make_scoped_refptr(extension)),
+      migrate_fs);
+}
+
+}  // namespace
+
+namespace extensions {
+
+AppDataMigrator::AppDataMigrator(Profile* profile, ExtensionRegistry* registry)
+    : profile_(profile), registry_(registry) {
+}
+
+bool AppDataMigrator::NeedsMigration(const Extension* old,
+                                     const Extension* extension) {
+  return old && old->is_legacy_packaged_app() && extension->is_platform_app();
+}
+
+void AppDataMigrator::DoMigrationAndReply(const Extension* old,
+                                          const Extension* extension,
+                                          const base::Closure& reply) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  DCHECK(NeedsMigration(old, extension));
+
+  // This should retrieve the general storage partition.
+  content::StoragePartition* old_partition =
+      BrowserContext::GetStoragePartitionForSite(
+          profile_, Extension::GetBaseURLFromExtensionId(extension->id()));
+
+  // Enable the new extension so we can access its storage partition.
+  bool old_was_disabled = registry_->AddEnabled(extension);
+
+  // This should create a new isolated partition for the new version of the
+  // extension.
+  StoragePartition* new_partition = BrowserContext::GetStoragePartitionForSite(
+      profile_, Extension::GetBaseURLFromExtensionId(extension->id()));
+
+  // Now, restore the enabled/disabled state of the new and old extensions.
+  if (!old_was_disabled) {

[cmumford, 2015/01/06 15:30:26]

No need for braces when scoping a single line of code.

Nit: Consider removing the "!" - maybe the code will be a bit more readable?

+    registry_->AddEnabled(old);
+  } else {
+    registry_->RemoveEnabled(extension->id());
+  }
+
+  // Begin the actual migration flow.

[cmumford, 2015/01/06 15:30:26]

Nit: does this comment add much?

+  MigrateLegacyPartition(old_partition, new_partition, extension, reply);
+}
+
+}  // namespace extensions