Add an option to specify requested fields for fetching metadata.

Fetching metadata is heavy, and it may cause calling stat() even though
it's not needed (is_directory is obtainable without stat()).

This CL adds the option. Backends will be updated to reflect it separately.
Also, as another step base::File::Info will be replaced with storage::Entry
or something similar with scoped_ptr's as members, to avoid reading
a member which was not requested in |fields|.

TEST=All current tests pass. But not really used yet, as backends ignore it.
BUG=558191

Review URL: https://codereview.chromium.org/1455403003

Cr-Commit-Position: refs/heads/master@{#360585}

12 files changed, 42 insertions, 18 deletions

diff --git a/storage/browser/fileapi/async_file_util.h b/storage/browser/fileapi/async_file_util.h
index eab6af7..799396b 100644
--- a/storage/browser/fileapi/async_file_util.h
+++ b/storage/browser/fileapi/async_file_util.h
@@ -80,6 +80,7 @@ class AsyncFileUtil {
   typedef base::Callback<void(int64 size)> CopyFileProgressCallback;
 
   typedef FileSystemOperation::CopyOrMoveOption CopyOrMoveOption;
+  typedef FileSystemOperation::GetMetadataField GetMetadataField;
 
   // Creates an AsyncFileUtil instance which performs file operations on
   // local native file system. The created instance assumes
@@ -149,10 +150,10 @@ class AsyncFileUtil {
   // - File::FILE_ERROR_NOT_FOUND if the file doesn't exist.
   // - Other error code if there was an error while retrieving the file info.
   //
-  virtual void GetFileInfo(
-      scoped_ptr<FileSystemOperationContext> context,
-      const FileSystemURL& url,
-      const GetFileInfoCallback& callback) = 0;
+  virtual void GetFileInfo(scoped_ptr<FileSystemOperationContext> context,
+                           const FileSystemURL& url,
+                           int fields,
+                           const GetFileInfoCallback& callback) = 0;
 
   // Reads contents of a directory at |path|.
   //
diff --git a/storage/browser/fileapi/async_file_util_adapter.cc b/storage/browser/fileapi/async_file_util_adapter.cc
index 0de0f61..6a7664f 100644
--- a/storage/browser/fileapi/async_file_util_adapter.cc
+++ b/storage/browser/fileapi/async_file_util_adapter.cc
@@ -195,6 +195,7 @@ void AsyncFileUtilAdapter::CreateDirectory(
 void AsyncFileUtilAdapter::GetFileInfo(
     scoped_ptr<FileSystemOperationContext> context,
     const FileSystemURL& url,
+    int /* fields */,
     const GetFileInfoCallback& callback) {
   FileSystemOperationContext* context_ptr = context.release();
   GetFileInfoHelper* helper = new GetFileInfoHelper;
diff --git a/storage/browser/fileapi/async_file_util_adapter.h b/storage/browser/fileapi/async_file_util_adapter.h
index 9c661a6..7a126b0 100644
--- a/storage/browser/fileapi/async_file_util_adapter.h
+++ b/storage/browser/fileapi/async_file_util_adapter.h
@@ -52,6 +52,7 @@ class STORAGE_EXPORT AsyncFileUtilAdapter
                        const StatusCallback& callback) override;
   void GetFileInfo(scoped_ptr<FileSystemOperationContext> context,
                    const FileSystemURL& url,
+                   int /* fields */,
                    const GetFileInfoCallback& callback) override;
   void ReadDirectory(scoped_ptr<FileSystemOperationContext> context,
                      const FileSystemURL& url,
diff --git a/storage/browser/fileapi/copy_or_move_operation_delegate.cc b/storage/browser/fileapi/copy_or_move_operation_delegate.cc
index cf4692b..715999b 100644
--- a/storage/browser/fileapi/copy_or_move_operation_delegate.cc
+++ b/storage/browser/fileapi/copy_or_move_operation_delegate.cc
@@ -391,7 +391,8 @@ class StreamCopyOrMoveImpl
     // a directory. To check errors before destination file creation,
     // check metadata first.
     operation_runner_->GetMetadata(
-        src_url_,
+        src_url_, FileSystemOperation::GET_METADATA_FIELD_IS_DIRECTORY |
+                      FileSystemOperation::GET_METADATA_FIELD_LAST_MODIFIED,
         base::Bind(&StreamCopyOrMoveImpl::RunAfterGetMetadataForSource,
                    weak_factory_.GetWeakPtr(), callback));
   }
@@ -884,7 +885,7 @@ void CopyOrMoveOperationDelegate::PostProcessDirectory(
   }
 
   operation_runner()->GetMetadata(
-      src_url,
+      src_url, FileSystemOperation::GET_METADATA_FIELD_LAST_MODIFIED,
       base::Bind(
           &CopyOrMoveOperationDelegate::PostProcessDirectoryAfterGetMetadata,
           weak_factory_.GetWeakPtr(), src_url, callback));
diff --git a/storage/browser/fileapi/file_system_context.cc b/storage/browser/fileapi/file_system_context.cc
index 7b280c8..8c099e7d 100644
--- a/storage/browser/fileapi/file_system_context.cc
+++ b/storage/browser/fileapi/file_system_context.cc
@@ -626,8 +626,12 @@ void FileSystemContext::DidOpenFileSystemForResolveURL(
     DCHECK(result);
   }
 
+  // TODO(mtomasz): Not all fields should be required for ResolveURL.
   operation_runner()->GetMetadata(
-      url, base::Bind(&DidGetMetadataForResolveURL, path, callback, info));
+      url, FileSystemOperation::GET_METADATA_FIELD_IS_DIRECTORY |
+               FileSystemOperation::GET_METADATA_FIELD_SIZE |
+               FileSystemOperation::GET_METADATA_FIELD_LAST_MODIFIED,
+      base::Bind(&DidGetMetadataForResolveURL, path, callback, info));
 }
 
 }  // namespace storage
diff --git a/storage/browser/fileapi/file_system_dir_url_request_job.cc b/storage/browser/fileapi/file_system_dir_url_request_job.cc
index 598b87a..c053773 100644
--- a/storage/browser/fileapi/file_system_dir_url_request_job.cc
+++ b/storage/browser/fileapi/file_system_dir_url_request_job.cc
@@ -157,7 +157,8 @@ void FileSystemDirURLRequestJob::GetMetadata(size_t index) {
       url_.path().Append(base::FilePath(entry.name)));
   DCHECK(url.is_valid());
   file_system_context_->operation_runner()->GetMetadata(
-      url,
+      url, FileSystemOperation::GET_METADATA_FIELD_SIZE |
+               FileSystemOperation::GET_METADATA_FIELD_LAST_MODIFIED,
       base::Bind(&FileSystemDirURLRequestJob::DidGetMetadata, this, index));
 }
 
diff --git a/storage/browser/fileapi/file_system_operation.h b/storage/browser/fileapi/file_system_operation.h
index b9e6f95..8580b35 100644
--- a/storage/browser/fileapi/file_system_operation.h
+++ b/storage/browser/fileapi/file_system_operation.h
@@ -227,6 +227,14 @@ class FileSystemOperation {
     OPTION_PRESERVE_LAST_MODIFIED,
   };
 
+  // Fields requested for the GetMetadata method. Used as a bitmask.
+  enum GetMetadataField {
+    GET_METADATA_FIELD_NONE = 0,
+    GET_METADATA_FIELD_SIZE = 1 << 0,
+    GET_METADATA_FIELD_IS_DIRECTORY = 1 << 1,
+    GET_METADATA_FIELD_LAST_MODIFIED = 1 << 2
+  };
+
   // Used for Write().
   typedef base::Callback<void(base::File::Error result,
                               int64 bytes,
@@ -302,6 +310,7 @@ class FileSystemOperation {
 
   // Gets the metadata of a file or directory at |path|.
   virtual void GetMetadata(const FileSystemURL& path,
+                           int fields,
                            const GetMetadataCallback& callback) = 0;
 
   // Reads contents of a directory at |path|.
diff --git a/storage/browser/fileapi/file_system_operation_impl.cc b/storage/browser/fileapi/file_system_operation_impl.cc
index 79cf89e..b6a6997 100644
--- a/storage/browser/fileapi/file_system_operation_impl.cc
+++ b/storage/browser/fileapi/file_system_operation_impl.cc
@@ -131,7 +131,7 @@ void FileSystemOperationImpl::DirectoryExists(const FileSystemURL& url,
                                               const StatusCallback& callback) {
   DCHECK(SetPendingOperationType(kOperationDirectoryExists));
   async_file_util_->GetFileInfo(
-      operation_context_.Pass(), url,
+      operation_context_.Pass(), url, GET_METADATA_FIELD_IS_DIRECTORY,
       base::Bind(&FileSystemOperationImpl::DidDirectoryExists,
                  weak_factory_.GetWeakPtr(), callback));
 }
@@ -140,15 +140,17 @@ void FileSystemOperationImpl::FileExists(const FileSystemURL& url,
                                          const StatusCallback& callback) {
   DCHECK(SetPendingOperationType(kOperationFileExists));
   async_file_util_->GetFileInfo(
-      operation_context_.Pass(), url,
+      operation_context_.Pass(), url, GET_METADATA_FIELD_IS_DIRECTORY,
       base::Bind(&FileSystemOperationImpl::DidFileExists,
                  weak_factory_.GetWeakPtr(), callback));
 }
 
-void FileSystemOperationImpl::GetMetadata(
-    const FileSystemURL& url, const GetMetadataCallback& callback) {
+void FileSystemOperationImpl::GetMetadata(const FileSystemURL& url,
+                                          int fields,
+                                          const GetMetadataCallback& callback) {
   DCHECK(SetPendingOperationType(kOperationGetMetadata));
-  async_file_util_->GetFileInfo(operation_context_.Pass(), url, callback);
+  async_file_util_->GetFileInfo(operation_context_.Pass(), url, fields,
+                                callback);
 }
 
 void FileSystemOperationImpl::ReadDirectory(
diff --git a/storage/browser/fileapi/file_system_operation_impl.h b/storage/browser/fileapi/file_system_operation_impl.h
index 6f4b662..26a434e 100644
--- a/storage/browser/fileapi/file_system_operation_impl.h
+++ b/storage/browser/fileapi/file_system_operation_impl.h
@@ -53,6 +53,7 @@ class STORAGE_EXPORT FileSystemOperationImpl
   void FileExists(const FileSystemURL& url,
                   const StatusCallback& callback) override;
   void GetMetadata(const FileSystemURL& url,
+                   int fields,
                    const GetMetadataCallback& callback) override;
   void ReadDirectory(const FileSystemURL& url,
                      const ReadDirectoryCallback& callback) override;
diff --git a/storage/browser/fileapi/file_system_operation_runner.cc b/storage/browser/fileapi/file_system_operation_runner.cc
index 1648055..4b5d422 100644
--- a/storage/browser/fileapi/file_system_operation_runner.cc
+++ b/storage/browser/fileapi/file_system_operation_runner.cc
@@ -175,6 +175,7 @@ OperationID FileSystemOperationRunner::FileExists(
 
 OperationID FileSystemOperationRunner::GetMetadata(
     const FileSystemURL& url,
+    int fields,
     const GetMetadataCallback& callback) {
   base::File::Error error = base::File::FILE_OK;
   FileSystemOperation* operation =
@@ -186,10 +187,9 @@ OperationID FileSystemOperationRunner::GetMetadata(
     return handle.id;
   }
   PrepareForRead(handle.id, url);
-  operation->GetMetadata(
-      url,
-      base::Bind(&FileSystemOperationRunner::DidGetMetadata, AsWeakPtr(),
-                 handle, callback));
+  operation->GetMetadata(url, fields,
+                         base::Bind(&FileSystemOperationRunner::DidGetMetadata,
+                                    AsWeakPtr(), handle, callback));
   return handle.id;
 }
 
diff --git a/storage/browser/fileapi/file_system_operation_runner.h b/storage/browser/fileapi/file_system_operation_runner.h
index 0493e4c..1421e1a 100644
--- a/storage/browser/fileapi/file_system_operation_runner.h
+++ b/storage/browser/fileapi/file_system_operation_runner.h
@@ -48,6 +48,7 @@ class STORAGE_EXPORT FileSystemOperationRunner
   typedef FileSystemOperation::CopyFileProgressCallback
       CopyFileProgressCallback;
   typedef FileSystemOperation::CopyOrMoveOption CopyOrMoveOption;
+  typedef FileSystemOperation::GetMetadataField GetMetadataField;
 
   typedef int OperationID;
 
@@ -98,6 +99,7 @@ class STORAGE_EXPORT FileSystemOperationRunner
 
   // Gets the metadata of a file or directory at |url|.
   OperationID GetMetadata(const FileSystemURL& url,
+                          int fields,
                           const GetMetadataCallback& callback);
 
   // Reads contents of a directory at |url|.
diff --git a/storage/browser/fileapi/file_system_url_request_job.cc b/storage/browser/fileapi/file_system_url_request_job.cc
index 6c33fc8..8edcb3d 100644
--- a/storage/browser/fileapi/file_system_url_request_job.cc
+++ b/storage/browser/fileapi/file_system_url_request_job.cc
@@ -165,7 +165,8 @@ void FileSystemURLRequestJob::StartAsync() {
     return;
   }
   file_system_context_->operation_runner()->GetMetadata(
-      url_,
+      url_, FileSystemOperation::GET_METADATA_FIELD_IS_DIRECTORY |
+                FileSystemOperation::GET_METADATA_FIELD_SIZE,
       base::Bind(&FileSystemURLRequestJob::DidGetMetadata,
                  weak_factory_.GetWeakPtr()));
 }