mediaview: Implement ArcDocumentsProviderBackendDelegate.

chrome/browser/chromeos/arc/fileapi/arc_documents_provider_file_stream_reader.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 "chrome/browser/chromeos/arc/fileapi/arc_documents_provider_file_stream_reader.h"
+
+#include "base/bind.h"
+#include "base/memory/ptr_util.h"
+#include "chrome/browser/chromeos/arc/fileapi/arc_content_file_system_file_stream_reader.h"
+#include "content/public/browser/browser_thread.h"
+#include "net/base/net_errors.h"
+#include "url/gurl.h"
+
+using content::BrowserThread;
+
+namespace arc {
+
+ArcDocumentsProviderFileStreamReader::ArcDocumentsProviderFileStreamReader(
+    int64_t offset)
+    : offset_(offset), resolved_(false), weak_ptr_factory_(this) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+}
+
+ArcDocumentsProviderFileStreamReader::~ArcDocumentsProviderFileStreamReader() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+}
+
+void ArcDocumentsProviderFileStreamReader::SetContentUrl(
+    const GURL& content_url) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  DCHECK(!resolved_);
+
+  if (content_url.is_valid()) {
+    underlying_reader_ = base::MakeUnique<ArcContentFileSystemFileStreamReader>(
+        content_url, offset_);
+  }
+  resolved_ = true;
+
+  for (const base::Closure& callback : pending_operations_) {
+    callback.Run();
+  }
+  pending_operations_.clear();
+}
+
+base::WeakPtr<ArcDocumentsProviderFileStreamReader>
+ArcDocumentsProviderFileStreamReader::GetWeakPtr() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  return weak_ptr_factory_.GetWeakPtr();
+}
+
+int ArcDocumentsProviderFileStreamReader::Read(
+    net::IOBuffer* buffer,
+    int buffer_length,
+    const net::CompletionCallback& callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  if (!resolved_) {
+    pending_operations_.emplace_back(base::Bind(
+        base::IgnoreResult(&ArcDocumentsProviderFileStreamReader::Read),
+        weak_ptr_factory_.GetWeakPtr(), buffer, buffer_length, callback));
+    return net::ERR_IO_PENDING;
+  }
+  if (!underlying_reader_)
+    return net::ERR_FILE_NOT_FOUND;
+  return underlying_reader_->Read(buffer, buffer_length, callback);
+}
+
+int64_t ArcDocumentsProviderFileStreamReader::GetLength(
+    const net::Int64CompletionCallback& callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  if (!resolved_) {
+    pending_operations_.emplace_back(base::Bind(
+        base::IgnoreResult(&ArcDocumentsProviderFileStreamReader::GetLength),
+        weak_ptr_factory_.GetWeakPtr(), callback));
+    return net::ERR_IO_PENDING;
+  }
+  if (!underlying_reader_)
+    return net::ERR_FILE_NOT_FOUND;
+  return underlying_reader_->GetLength(callback);
+}
+
+}  // namespace arc