Remove some PlatformFile instances from ChromeOS Drive.

chrome/browser/chromeos/drive/local_file_reader.cc

Index: chrome/browser/chromeos/drive/local_file_reader.cc
diff --git a/chrome/browser/chromeos/drive/local_file_reader.cc b/chrome/browser/chromeos/drive/local_file_reader.cc
index f7cf425a3cfcbeaf7c4ea7079a7b8cc419b3aec7..062bbb8e46b8b75332bcaaaa1d1f89432abc10ef 100644
--- a/chrome/browser/chromeos/drive/local_file_reader.cc
+++ b/chrome/browser/chromeos/drive/local_file_reader.cc
@@ -4,15 +4,9 @@
 
 #include "chrome/browser/chromeos/drive/local_file_reader.h"
 
-#include <errno.h>
-
 #include "base/bind.h"
-#include "base/bind_helpers.h"
 #include "base/files/file_path.h"
-#include "base/location.h"
-#include "base/platform_file.h"
 #include "base/sequenced_task_runner.h"
-#include "base/task_runner_util.h"
 #include "net/base/completion_callback.h"
 #include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
@@ -20,157 +14,55 @@
 namespace drive {
 namespace util {
 
-namespace {
-
-// Opens the file at |file_path| and seeks to the |offset| from begin.
-// Returns the net::Error code. If succeeded, |platform_file| is set to point
-// the opened file.
-// This function should run on the blocking pool.
-int OpenAndSeekOnBlockingPool(const base::FilePath& file_path,
-                              int64 offset,
-                              base::PlatformFile* platform_file) {
-  DCHECK(platform_file);
-  DCHECK_EQ(base::kInvalidPlatformFileValue, *platform_file);
-
-  // First of all, open the file.
-  const int open_flags = base::PLATFORM_FILE_OPEN |
-                         base::PLATFORM_FILE_READ |
-                         base::PLATFORM_FILE_ASYNC;
-  base::PlatformFileError error = base::PLATFORM_FILE_ERROR_FAILED;
-  base::PlatformFile file =
-      base::CreatePlatformFile(file_path, open_flags, NULL, &error);
-  if (file == base::kInvalidPlatformFileValue) {
-    DCHECK_NE(base::PLATFORM_FILE_OK, error);
-    return net::FileErrorToNetError(static_cast<base::File::Error>(error));
-  }
-
-  // If succeeded, seek to the |offset| from begin.
-  int64 position = base::SeekPlatformFile(
-      file, base::PLATFORM_FILE_FROM_BEGIN, offset);
-  if (position < 0) {
-    // If failed, close the file and return an error.
-    base::ClosePlatformFile(file);
-    return net::ERR_FAILED;
-  }
-
-  *platform_file = file;
-  return net::OK;
-}
-
-// Reads the data from the |platform_file| and copies it to the |buffer| at
-// most |buffer_length| size. Returns the number of copied bytes if succeeded,
-// or the net::Error code.
-// This function should run on the blocking pool.
-int ReadOnBlockingPool(base::PlatformFile platform_file,
-                       scoped_refptr<net::IOBuffer> buffer,
-                       int buffer_length) {
-  DCHECK_NE(base::kInvalidPlatformFileValue, platform_file);
-  int result = base::ReadPlatformFileCurPosNoBestEffort(
-      platform_file, buffer->data(), buffer_length);
-  return result < 0 ? net::MapSystemError(errno) : result;
-}
-
-// Posts a task to close the |platform_file| into |task_runner|.
-// Or, if |platform_file| is kInvalidPlatformFileValue, does nothing.
-void PostCloseIfNeeded(base::TaskRunner* task_runner,
-                       base::PlatformFile platform_file) {
-  DCHECK(task_runner);
-  if (platform_file != base::kInvalidPlatformFileValue) {
-    task_runner->PostTask(
-        FROM_HERE,
-        base::Bind(
-            base::IgnoreResult(&base::ClosePlatformFile), platform_file));
-  }
-}
-
-}  // namespace
-
-class LocalFileReader::ScopedPlatformFile {
- public:
-  explicit ScopedPlatformFile(base::TaskRunner* task_runner)
-      : task_runner_(task_runner),
-        platform_file_(base::kInvalidPlatformFileValue) {
-    DCHECK(task_runner);
-  }
-
-  ~ScopedPlatformFile() {
-    PostCloseIfNeeded(task_runner_.get(), platform_file_);
-  }
-
-  base::PlatformFile* ptr() { return &platform_file_; }
-
-  base::PlatformFile release() {
-    base::PlatformFile result = platform_file_;
-    platform_file_ = base::kInvalidPlatformFileValue;
-    return result;
-  }
-
- private:
-  scoped_refptr<base::TaskRunner> task_runner_;
-  base::PlatformFile platform_file_;
-
-  DISALLOW_COPY_AND_ASSIGN(ScopedPlatformFile);
-};
-
 LocalFileReader::LocalFileReader(
     base::SequencedTaskRunner* sequenced_task_runner)
-    : sequenced_task_runner_(sequenced_task_runner),
-      platform_file_(base::kInvalidPlatformFileValue),
+    : file_stream_(NULL, sequenced_task_runner),
       weak_ptr_factory_(this) {
-  DCHECK(sequenced_task_runner_.get());
 }
 
 LocalFileReader::~LocalFileReader() {
-  PostCloseIfNeeded(sequenced_task_runner_.get(), platform_file_);
 }
 
 void LocalFileReader::Open(const base::FilePath& file_path,
                            int64 offset,
                            const net::CompletionCallback& callback) {
   DCHECK(!callback.is_null());
-  DCHECK_EQ(base::kInvalidPlatformFileValue, platform_file_);
-
-  ScopedPlatformFile* platform_file =
-      new ScopedPlatformFile(sequenced_task_runner_.get());
-  base::PostTaskAndReplyWithResult(
-      sequenced_task_runner_.get(),
-      FROM_HERE,
-      base::Bind(
-          &OpenAndSeekOnBlockingPool, file_path, offset, platform_file->ptr()),
-      base::Bind(&LocalFileReader::OpenAfterBlockingPoolTask,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 callback,
-                 base::Owned(platform_file)));
+  int flags = base::File::FLAG_OPEN | base::File::FLAG_READ |
+              base::PLATFORM_FILE_ASYNC;
+
+  int rv = file_stream_.Open(file_path, flags,
+                             Bind(&LocalFileReader::DidOpen,
+                                  weak_ptr_factory_.GetWeakPtr(),
+                                  callback, offset));
+  DCHECK_EQ(rv, net::ERR_IO_PENDING);
 }
 
 void LocalFileReader::Read(net::IOBuffer* in_buffer,
                            int buffer_length,
                            const net::CompletionCallback& callback) {
   DCHECK(!callback.is_null());
-  DCHECK_NE(base::kInvalidPlatformFileValue, platform_file_);
-
-  scoped_refptr<net::IOBuffer> buffer(in_buffer);
-  base::PostTaskAndReplyWithResult(
-      sequenced_task_runner_.get(),
-      FROM_HERE,
-      base::Bind(&ReadOnBlockingPool, platform_file_, buffer, buffer_length),
-      callback);
+  DCHECK(file_stream_.IsOpen());
+  int rv = file_stream_.Read(in_buffer, buffer_length, callback);
+  DCHECK_EQ(rv, net::ERR_IO_PENDING);
 }
 
-void LocalFileReader::OpenAfterBlockingPoolTask(
-    const net::CompletionCallback& callback,
-    ScopedPlatformFile* platform_file,
-    int open_result) {
-  DCHECK(!callback.is_null());
-  DCHECK(platform_file);
-  DCHECK_EQ(base::kInvalidPlatformFileValue, platform_file_);
-
-  if (open_result == net::OK) {
-    DCHECK_NE(base::kInvalidPlatformFileValue, *platform_file->ptr());
-    platform_file_ = platform_file->release();
-  }
+void LocalFileReader::DidOpen(const net::CompletionCallback& callback,
+                              int64 offset,
+                              int error) {
+  if (error != net::OK)
+    return callback.Run(error);
+
+  int rv = file_stream_.Seek(net::FROM_BEGIN, offset,
+                             Bind(&LocalFileReader::DidSeek,
+                                  weak_ptr_factory_.GetWeakPtr(),
+                                  callback, offset));
+  DCHECK_EQ(rv, net::ERR_IO_PENDING);
+}
 
-  callback.Run(open_result);
+void LocalFileReader::DidSeek(const net::CompletionCallback& callback,
+                              int64 offset,
+                              int64 error) {
+  callback.Run(error == offset ? net::OK : net::ERR_FAILED);
 }
 
 }  // namespace util