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 "chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.h"
+#include "chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root_map.h"
+#include "content/public/browser/browser_thread.h"
+#include "net/base/io_buffer.h"
+#include "net/base/net_errors.h"
+#include "url/gurl.h"
+
+using content::BrowserThread;
+
+namespace arc {
+
+ArcDocumentsProviderFileStreamReader::ArcDocumentsProviderFileStreamReader(
+    const storage::FileSystemURL& url,
+    int64_t offset,
+    ArcDocumentsProviderRootMap* roots)
+    : offset_(offset), content_url_resolved_(false), weak_ptr_factory_(this) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  base::FilePath path;
+  ArcDocumentsProviderRoot* root = roots->ParseAndLookup(url, &path);
+  if (!root) {
+    content_url_resolved_ = true;
+    return;
+  }
+  root->ResolveToContentUrl(
+      path,
+      base::Bind(&ArcDocumentsProviderFileStreamReader::OnResolveToContentUrl,
+                 weak_ptr_factory_.GetWeakPtr()));
+}
+
+ArcDocumentsProviderFileStreamReader::~ArcDocumentsProviderFileStreamReader() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+}
+
+int ArcDocumentsProviderFileStreamReader::Read(
+    net::IOBuffer* buffer,
+    int buffer_length,
+    const net::CompletionCallback& callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  if (!content_url_resolved_) {
+    pending_operations_.emplace_back(base::Bind(
+        &ArcDocumentsProviderFileStreamReader::RunPendingRead,
+        base::Unretained(this), base::Passed(make_scoped_refptr(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 (!content_url_resolved_) {
+    pending_operations_.emplace_back(
+        base::Bind(&ArcDocumentsProviderFileStreamReader::RunPendingGetLength,
+                   base::Unretained(this), callback));
+    return net::ERR_IO_PENDING;
+  }
+  if (!underlying_reader_)
+    return net::ERR_FILE_NOT_FOUND;
+  return underlying_reader_->GetLength(callback);
+}
+
+void ArcDocumentsProviderFileStreamReader::OnResolveToContentUrl(
+    const GURL& content_url) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  DCHECK(!content_url_resolved_);
+
+  if (content_url.is_valid()) {
+    underlying_reader_ = base::MakeUnique<ArcContentFileSystemFileStreamReader>(
+        content_url, offset_);
+  }
+  content_url_resolved_ = true;
+
+  std::vector<base::Closure> pending_operations;
+  pending_operations.swap(pending_operations_);
+  for (const base::Closure& callback : pending_operations) {
+    callback.Run();
+  }
+}
+
+void ArcDocumentsProviderFileStreamReader::RunPendingRead(
+    scoped_refptr<net::IOBuffer> buffer,
+    int buffer_length,
+    const net::CompletionCallback& callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  DCHECK(content_url_resolved_);
+  int result =
+      underlying_reader_
+          ? underlying_reader_->Read(buffer.get(), buffer_length, callback)
+          : net::ERR_FILE_NOT_FOUND;
+  if (result != net::ERR_IO_PENDING)
+    callback.Run(result);
+}
+
+void ArcDocumentsProviderFileStreamReader::RunPendingGetLength(
+    const net::Int64CompletionCallback& callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  DCHECK(content_url_resolved_);
+  int64_t result = underlying_reader_ ? underlying_reader_->GetLength(callback)
+                                      : net::ERR_FILE_NOT_FOUND;
+  if (result != net::ERR_IO_PENDING)
+    callback.Run(result);
+}
+
+}  // namespace arc