4 files changed, 105 insertions, 0 deletions

diff --git a/sync/api/attachments/attachment_metadata.cc b/sync/api/attachments/attachment_metadata.cc
new file mode 100644
index 0000000..202de23
--- /dev/null
+++ b/sync/api/attachments/attachment_metadata.cc
@@ -0,0 +1,24 @@
+// 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 "sync/api/attachments/attachment_metadata.h"
+
+namespace syncer {
+
+AttachmentMetadata::AttachmentMetadata(const AttachmentId& id, size_t size)
+    : id_(id), size_(size) {
+}
+
+AttachmentMetadata::~AttachmentMetadata() {
+}
+
+const AttachmentId& AttachmentMetadata::GetId() const {
+  return id_;
+}
+
+size_t AttachmentMetadata::GetSize() const {
+  return size_;
+}
+
+}  // namespace syncer
diff --git a/sync/api/attachments/attachment_metadata.h b/sync/api/attachments/attachment_metadata.h
new file mode 100644
index 0000000..10761f8
--- /dev/null
+++ b/sync/api/attachments/attachment_metadata.h
@@ -0,0 +1,41 @@
+// 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.
+
+#ifndef SYNC_API_ATTACHMENTS_ATTACHMENT_METADATA_H_
+#define SYNC_API_ATTACHMENTS_ATTACHMENT_METADATA_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "sync/api/attachments/attachment_id.h"
+#include "sync/base/sync_export.h"
+
+namespace syncer {
+
+// This class represents immutable Attachment metadata.
+//
+// It is OK to copy and return AttachmentMetadata by value.
+class SYNC_EXPORT AttachmentMetadata {
+ public:
+  AttachmentMetadata(const AttachmentId& id, size_t size);
+  ~AttachmentMetadata();
+
+  // Default copy and assignment are welcome.
+
+  // Returns this attachment's id.
+  const AttachmentId& GetId() const;
+
+  // Returns this attachment's size in bytes.
+  size_t GetSize() const;
+
+ private:
+  AttachmentId id_;
+  size_t size_;
+};
+
+typedef std::vector<syncer::AttachmentMetadata> AttachmentMetadataList;
+
+}  // namespace syncer
+
+#endif  // SYNC_API_ATTACHMENTS_ATTACHMENT_METADATA_H_
diff --git a/sync/api/attachments/attachment_metadata_unittest.cc b/sync/api/attachments/attachment_metadata_unittest.cc
new file mode 100644
index 0000000..06477d0
--- /dev/null
+++ b/sync/api/attachments/attachment_metadata_unittest.cc
@@ -0,0 +1,21 @@
+// 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 "sync/api/attachments/attachment_metadata.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace syncer {
+
+class AttachmentMetadataTest : public testing::Test {};
+
+TEST_F(AttachmentMetadataTest, Create) {
+  AttachmentId id = AttachmentId::Create();
+  size_t size = 42;
+  AttachmentMetadata metadata(id, size);
+  EXPECT_EQ(metadata.GetId(), id);
+  EXPECT_EQ(metadata.GetSize(), size);
+}
+
+}  // namespace syncer
diff --git a/sync/api/attachments/attachment_store.h b/sync/api/attachments/attachment_store.h
index 3c41a27..6c7791a 100644
--- a/sync/api/attachments/attachment_store.h
+++ b/sync/api/attachments/attachment_store.h
@@ -10,6 +10,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "sync/api/attachments/attachment.h"
 #include "sync/api/attachments/attachment_id.h"
+#include "sync/api/attachments/attachment_metadata.h"
 #include "sync/base/sync_export.h"
 
 namespace base {
@@ -42,6 +43,9 @@ class SYNC_EXPORT AttachmentStoreBase {
                               scoped_ptr<AttachmentIdList>)> ReadCallback;
   typedef base::Callback<void(const Result&)> WriteCallback;
   typedef base::Callback<void(const Result&)> DropCallback;
+  typedef base::Callback<void(const Result&,
+                              scoped_ptr<AttachmentMetadataList>)>
+      ReadMetadataCallback;
 
   AttachmentStoreBase();
   virtual ~AttachmentStoreBase();
@@ -84,6 +88,21 @@ class SYNC_EXPORT AttachmentStoreBase {
   // successfully.
   virtual void Drop(const AttachmentIdList& ids,
                     const DropCallback& callback) = 0;
+
+  // Asynchronously reads metadata for the attachments identified by |ids|.
+  //
+  // |callback| will be invoked when finished. AttachmentStore will attempt to
+  // read metadata for all attachments specified in ids. If any of the
+  // metadata entries do not exist or could not be read, |callback|'s Result
+  // will be UNSPECIFIED_ERROR.
+  virtual void ReadMetadata(const AttachmentIdList& ids,
+                            const ReadMetadataCallback& callback) = 0;
+
+  // Asynchronously reads metadata for all attachments in the store.
+  //
+  // |callback| will be invoked when finished. If any of the metadata entries
+  // could not be read, |callback|'s Result will be UNSPECIFIED_ERROR.
+  virtual void ReadAllMetadata(const ReadMetadataCallback& callback) = 0;
 };
 
 // AttachmentStore is an interface exposed to data type and AttachmentService