[fsp] Add support for opening files.

This patch adds support to opening a file. It is currently no-op, and it is
not yet bound to fileapi.

In order to bound it to fileapi::AsyncFileUtil, we need to implement closing
operation, and reading operations first. Otherwise, creating a snapshot
(required by fileapi::AsyncFileUtil) is not possible.

TEST=unit_tests: *FileSystemProvider*OpenFile*
BUG=248427

Review URL: https://codereview.chromium.org/284443002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@270040 0039d316-1c4b-4281-b951-d872f2087c98

15 files changed, 506 insertions, 7 deletions

diff --git a/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_api.cc b/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_api.cc
index d080d52..67c0fa6 100644
--- a/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_api.cc
+++ b/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_api.cc
@@ -149,4 +149,24 @@ FileSystemProviderInternalReadDirectoryRequestedErrorFunction::RunWhenValid() {
   return true;
 }
 
+bool
+FileSystemProviderInternalOpenFileRequestedSuccessFunction::RunWhenValid() {
+  using api::file_system_provider_internal::OpenFileRequestedSuccess::Params;
+  scoped_ptr<Params> params(Params::Create(*args_));
+  EXTENSION_FUNCTION_VALIDATE(params);
+
+  FulfillRequest(scoped_ptr<RequestValue>(new RequestValue()),
+                 false /* has_more */);
+  return true;
+}
+
+bool FileSystemProviderInternalOpenFileRequestedErrorFunction::RunWhenValid() {
+  using api::file_system_provider_internal::OpenFileRequestedError::Params;
+  const scoped_ptr<Params> params(Params::Create(*args_));
+  EXTENSION_FUNCTION_VALIDATE(params);
+
+  RejectRequest(ProviderErrorToFileError(params->error));
+  return true;
+}
+
 }  // namespace extensions
diff --git a/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_api.h b/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_api.h
index 21102a6b..e1b2916 100644
--- a/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_api.h
+++ b/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_api.h
@@ -102,6 +102,30 @@ class FileSystemProviderInternalReadDirectoryRequestedErrorFunction
   virtual bool RunWhenValid() OVERRIDE;
 };
 
+class FileSystemProviderInternalOpenFileRequestedSuccessFunction
+    : public FileSystemProviderInternalFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION(
+      "fileSystemProviderInternal.openFileRequestedSuccess",
+      FILESYSTEMPROVIDERINTERNAL_OPENFILEREQUESTEDSUCCESS)
+
+ protected:
+  virtual ~FileSystemProviderInternalOpenFileRequestedSuccessFunction() {}
+  virtual bool RunWhenValid() OVERRIDE;
+};
+
+class FileSystemProviderInternalOpenFileRequestedErrorFunction
+    : public FileSystemProviderInternalFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION(
+      "fileSystemProviderInternal.openFileRequestedError",
+      FILESYSTEMPROVIDERINTERNAL_OPENFILEREQUESTEDERROR)
+
+ protected:
+  virtual ~FileSystemProviderInternalOpenFileRequestedErrorFunction() {}
+  virtual bool RunWhenValid() OVERRIDE;
+};
+
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_CHROMEOS_EXTENSIONS_FILE_SYSTEM_PROVIDER_FILE_SYSTEM_PROVIDER_API_H_
diff --git a/chrome/browser/chromeos/file_system_provider/fake_provided_file_system.cc b/chrome/browser/chromeos/file_system_provider/fake_provided_file_system.cc
index f27aeb0..aab2a83 100644
--- a/chrome/browser/chromeos/file_system_provider/fake_provided_file_system.cc
+++ b/chrome/browser/chromeos/file_system_provider/fake_provided_file_system.cc
@@ -118,6 +118,20 @@ void FakeProvidedFileSystem::ReadDirectory(
   }
 }
 
+void FakeProvidedFileSystem::OpenFile(
+    const base::FilePath& file_path,
+    OpenFileMode mode,
+    bool create,
+    const fileapi::AsyncFileUtil::StatusCallback& callback) {
+  if (file_path.AsUTF8Unsafe() != "/hello.txt" ||
+      mode == OPEN_FILE_MODE_WRITE || create) {
+    callback.Run(base::File::FILE_ERROR_SECURITY);
+    return;
+  }
+
+  callback.Run(base::File::FILE_OK);
+}
+
 const ProvidedFileSystemInfo& FakeProvidedFileSystem::GetFileSystemInfo()
     const {
   return file_system_info_;
diff --git a/chrome/browser/chromeos/file_system_provider/fake_provided_file_system.h b/chrome/browser/chromeos/file_system_provider/fake_provided_file_system.h
index 47dcdcf..2721dd0 100644
--- a/chrome/browser/chromeos/file_system_provider/fake_provided_file_system.h
+++ b/chrome/browser/chromeos/file_system_provider/fake_provided_file_system.h
@@ -34,6 +34,11 @@ class FakeProvidedFileSystem : public ProvidedFileSystemInterface {
   virtual void ReadDirectory(
       const base::FilePath& directory_path,
       const fileapi::AsyncFileUtil::ReadDirectoryCallback& callback) OVERRIDE;
+  virtual void OpenFile(
+      const base::FilePath& file_path,
+      OpenFileMode mode,
+      bool create,
+      const fileapi::AsyncFileUtil::StatusCallback& callback) OVERRIDE;
   virtual const ProvidedFileSystemInfo& GetFileSystemInfo() const OVERRIDE;
   virtual RequestManager* GetRequestManager() OVERRIDE;
 
diff --git a/chrome/browser/chromeos/file_system_provider/operations/open_file.cc b/chrome/browser/chromeos/file_system_provider/operations/open_file.cc
new file mode 100644
index 0000000..a1a6e16
--- /dev/null
+++ b/chrome/browser/chromeos/file_system_provider/operations/open_file.cc
@@ -0,0 +1,67 @@
+// 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 "chrome/browser/chromeos/file_system_provider/operations/open_file.h"
+
+#include <string>
+
+#include "chrome/common/extensions/api/file_system_provider.h"
+#include "chrome/common/extensions/api/file_system_provider_internal.h"
+
+namespace chromeos {
+namespace file_system_provider {
+namespace operations {
+
+OpenFile::OpenFile(extensions::EventRouter* event_router,
+                   const ProvidedFileSystemInfo& file_system_info,
+                   const base::FilePath& file_path,
+                   ProvidedFileSystemInterface::OpenFileMode mode,
+                   bool create,
+                   const fileapi::AsyncFileUtil::StatusCallback& callback)
+    : Operation(event_router, file_system_info),
+      file_path_(file_path),
+      mode_(mode),
+      create_(create),
+      callback_(callback) {
+}
+
+OpenFile::~OpenFile() {
+}
+
+bool OpenFile::Execute(int request_id) {
+  scoped_ptr<base::ListValue> values(new base::ListValue);
+  values->AppendString(file_path_.AsUTF8Unsafe());
+
+  switch (mode_) {
+    case ProvidedFileSystemInterface::OPEN_FILE_MODE_READ:
+      values->AppendString(extensions::api::file_system_provider::ToString(
+          extensions::api::file_system_provider::OPEN_FILE_MODE_READ));
+      break;
+    case ProvidedFileSystemInterface::OPEN_FILE_MODE_WRITE:
+      values->AppendString(extensions::api::file_system_provider::ToString(
+          extensions::api::file_system_provider::OPEN_FILE_MODE_WRITE));
+      break;
+  }
+
+  values->AppendBoolean(create_);
+
+  return SendEvent(
+      request_id,
+      extensions::api::file_system_provider::OnOpenFileRequested::kEventName,
+      values.Pass());
+}
+
+void OpenFile::OnSuccess(int /* request_id */,
+                         scoped_ptr<RequestValue> result,
+                         bool has_next) {
+  callback_.Run(base::File::FILE_OK);
+}
+
+void OpenFile::OnError(int /* request_id */, base::File::Error error) {
+  callback_.Run(error);
+}
+
+}  // namespace operations
+}  // namespace file_system_provider
+}  // namespace chromeos
diff --git a/chrome/browser/chromeos/file_system_provider/operations/open_file.h b/chrome/browser/chromeos/file_system_provider/operations/open_file.h
new file mode 100644
index 0000000..efe0a53
--- /dev/null
+++ b/chrome/browser/chromeos/file_system_provider/operations/open_file.h
@@ -0,0 +1,61 @@
+// 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 CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_OPERATIONS_OPEN_FILE_H_
+#define CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_OPERATIONS_OPEN_FILE_H_
+
+#include "base/files/file.h"
+#include "base/memory/scoped_ptr.h"
+#include "chrome/browser/chromeos/file_system_provider/operations/operation.h"
+#include "chrome/browser/chromeos/file_system_provider/provided_file_system_info.h"
+#include "chrome/browser/chromeos/file_system_provider/provided_file_system_interface.h"
+#include "chrome/browser/chromeos/file_system_provider/request_value.h"
+#include "webkit/browser/fileapi/async_file_util.h"
+
+namespace base {
+class FilePath;
+}  // namespace base
+
+namespace extensions {
+class EventRouter;
+}  // namespace extensions
+
+namespace chromeos {
+namespace file_system_provider {
+namespace operations {
+
+// Opens a file for either read or write, with optionally creating the file
+// first. Note, that this is part of fileapi::CreateOrOpen file, but it does
+// not download the file locally. Created per request.
+class OpenFile : public Operation {
+ public:
+  OpenFile(extensions::EventRouter* event_router,
+           const ProvidedFileSystemInfo& file_system_info,
+           const base::FilePath& file_path,
+           ProvidedFileSystemInterface::OpenFileMode mode,
+           bool create,
+           const fileapi::AsyncFileUtil::StatusCallback& callback);
+  virtual ~OpenFile();
+
+  // Operation overrides.
+  virtual bool Execute(int request_id) OVERRIDE;
+  virtual void OnSuccess(int request_id,
+                         scoped_ptr<RequestValue> result,
+                         bool has_next) OVERRIDE;
+  virtual void OnError(int request_id, base::File::Error error) OVERRIDE;
+
+ private:
+  base::FilePath file_path_;
+  ProvidedFileSystemInterface::OpenFileMode mode_;
+  bool create_;
+  const fileapi::AsyncFileUtil::StatusCallback callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(OpenFile);
+};
+
+}  // namespace operations
+}  // namespace file_system_provider
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_OPERATIONS_OPEN_FILE_H_
diff --git a/chrome/browser/chromeos/file_system_provider/operations/open_file_unittest.cc b/chrome/browser/chromeos/file_system_provider/operations/open_file_unittest.cc
new file mode 100644
index 0000000..02fff32
--- /dev/null
+++ b/chrome/browser/chromeos/file_system_provider/operations/open_file_unittest.cc
@@ -0,0 +1,215 @@
+// 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 <string>
+#include <vector>
+
+#include "base/files/file.h"
+#include "base/files/file_path.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/scoped_vector.h"
+#include "chrome/browser/chromeos/file_system_provider/operations/open_file.h"
+#include "chrome/browser/chromeos/file_system_provider/provided_file_system_interface.h"
+#include "chrome/common/extensions/api/file_system_provider.h"
+#include "chrome/common/extensions/api/file_system_provider_internal.h"
+#include "extensions/browser/event_router.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "webkit/browser/fileapi/async_file_util.h"
+
+namespace chromeos {
+namespace file_system_provider {
+namespace operations {
+namespace {
+
+const char kExtensionId[] = "mbflcebpggnecokmikipoihdbecnjfoj";
+const int kFileSystemId = 1;
+const int kRequestId = 2;
+const base::FilePath::CharType kFilePath[] = "/directory/blueberries.txt";
+
+// Fake event dispatcher implementation with extra logging capability. Acts as
+// a providing extension end-point.
+class LoggingDispatchEventImpl {
+ public:
+  explicit LoggingDispatchEventImpl(bool dispatch_reply)
+      : dispatch_reply_(dispatch_reply) {}
+  virtual ~LoggingDispatchEventImpl() {}
+
+  bool OnDispatchEventImpl(scoped_ptr<extensions::Event> event) {
+    events_.push_back(event->DeepCopy());
+    return dispatch_reply_;
+  }
+
+  ScopedVector<extensions::Event>& events() { return events_; }
+
+ private:
+  ScopedVector<extensions::Event> events_;
+  bool dispatch_reply_;
+
+  DISALLOW_COPY_AND_ASSIGN(LoggingDispatchEventImpl);
+};
+
+// Callback invocation logger. Acts as a fileapi end-point.
+class CallbackLogger {
+ public:
+  CallbackLogger() : weak_ptr_factory_(this) {}
+  virtual ~CallbackLogger() {}
+
+  void OnOpenFile(base::File::Error result) { events_.push_back(result); }
+
+  std::vector<base::File::Error>& events() { return events_; }
+
+  base::WeakPtr<CallbackLogger> GetWeakPtr() {
+    return weak_ptr_factory_.GetWeakPtr();
+  }
+
+ private:
+  std::vector<base::File::Error> events_;
+  base::WeakPtrFactory<CallbackLogger> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(CallbackLogger);
+};
+
+}  // namespace
+
+class FileSystemProviderOperationsOpenFileTest : public testing::Test {
+ protected:
+  FileSystemProviderOperationsOpenFileTest() {}
+  virtual ~FileSystemProviderOperationsOpenFileTest() {}
+
+  virtual void SetUp() OVERRIDE {
+    file_system_info_ =
+        ProvidedFileSystemInfo(kExtensionId,
+                               kFileSystemId,
+                               "" /* file_system_name */,
+                               base::FilePath() /* mount_path */);
+  }
+
+  ProvidedFileSystemInfo file_system_info_;
+};
+
+TEST_F(FileSystemProviderOperationsOpenFileTest, Execute) {
+  LoggingDispatchEventImpl dispatcher(true /* dispatch_reply */);
+  CallbackLogger callback_logger;
+
+  OpenFile open_file(
+      NULL,
+      file_system_info_,
+      base::FilePath::FromUTF8Unsafe(kFilePath),
+      ProvidedFileSystemInterface::OPEN_FILE_MODE_READ,
+      false /* create */,
+      base::Bind(&CallbackLogger::OnOpenFile, callback_logger.GetWeakPtr()));
+  open_file.SetDispatchEventImplForTesting(
+      base::Bind(&LoggingDispatchEventImpl::OnDispatchEventImpl,
+                 base::Unretained(&dispatcher)));
+
+  EXPECT_TRUE(open_file.Execute(kRequestId));
+
+  ASSERT_EQ(1u, dispatcher.events().size());
+  extensions::Event* event = dispatcher.events()[0];
+  EXPECT_EQ(
+      extensions::api::file_system_provider::OnOpenFileRequested::kEventName,
+      event->event_name);
+  base::ListValue* event_args = event->event_args.get();
+  ASSERT_EQ(5u, event_args->GetSize());
+
+  int event_file_system_id = -1;
+  EXPECT_TRUE(event_args->GetInteger(0, &event_file_system_id));
+  EXPECT_EQ(kFileSystemId, event_file_system_id);
+
+  int event_request_id = -1;
+  EXPECT_TRUE(event_args->GetInteger(1, &event_request_id));
+  EXPECT_EQ(kRequestId, event_request_id);
+
+  std::string event_file_path;
+  EXPECT_TRUE(event_args->GetString(2, &event_file_path));
+  EXPECT_EQ(kFilePath, event_file_path);
+
+  std::string event_file_open_mode;
+  EXPECT_TRUE(event_args->GetString(3, &event_file_open_mode));
+  const std::string expected_file_open_mode =
+      extensions::api::file_system_provider::ToString(
+          extensions::api::file_system_provider::OPEN_FILE_MODE_READ);
+  EXPECT_EQ(expected_file_open_mode, event_file_open_mode);
+
+  bool event_create;
+  EXPECT_TRUE(event_args->GetBoolean(4, &event_create));
+  EXPECT_FALSE(event_create);
+}
+
+TEST_F(FileSystemProviderOperationsOpenFileTest, Execute_NoListener) {
+  LoggingDispatchEventImpl dispatcher(false /* dispatch_reply */);
+  CallbackLogger callback_logger;
+
+  OpenFile open_file(
+      NULL,
+      file_system_info_,
+      base::FilePath::FromUTF8Unsafe(kFilePath),
+      ProvidedFileSystemInterface::OPEN_FILE_MODE_READ,
+      false /* create */,
+      base::Bind(&CallbackLogger::OnOpenFile, callback_logger.GetWeakPtr()));
+  open_file.SetDispatchEventImplForTesting(
+      base::Bind(&LoggingDispatchEventImpl::OnDispatchEventImpl,
+                 base::Unretained(&dispatcher)));
+
+  EXPECT_FALSE(open_file.Execute(kRequestId));
+}
+
+TEST_F(FileSystemProviderOperationsOpenFileTest, OnSuccess) {
+  using extensions::api::file_system_provider::EntryMetadata;
+  using extensions::api::file_system_provider_internal::
+      OpenFileRequestedSuccess::Params;
+
+  LoggingDispatchEventImpl dispatcher(true /* dispatch_reply */);
+  CallbackLogger callback_logger;
+
+  OpenFile open_file(
+      NULL,
+      file_system_info_,
+      base::FilePath::FromUTF8Unsafe(kFilePath),
+      ProvidedFileSystemInterface::OPEN_FILE_MODE_READ,
+      false /* create */,
+      base::Bind(&CallbackLogger::OnOpenFile, callback_logger.GetWeakPtr()));
+  open_file.SetDispatchEventImplForTesting(
+      base::Bind(&LoggingDispatchEventImpl::OnDispatchEventImpl,
+                 base::Unretained(&dispatcher)));
+
+  EXPECT_TRUE(open_file.Execute(kRequestId));
+
+  open_file.OnSuccess(kRequestId,
+                      scoped_ptr<RequestValue>(new RequestValue()),
+                      false /* has_next */);
+  ASSERT_EQ(1u, callback_logger.events().size());
+  EXPECT_EQ(base::File::FILE_OK, callback_logger.events()[0]);
+}
+
+TEST_F(FileSystemProviderOperationsOpenFileTest, OnError) {
+  using extensions::api::file_system_provider::EntryMetadata;
+  using extensions::api::file_system_provider_internal::OpenFileRequestedError::
+      Params;
+
+  LoggingDispatchEventImpl dispatcher(true /* dispatch_reply */);
+  CallbackLogger callback_logger;
+
+  OpenFile open_file(
+      NULL,
+      file_system_info_,
+      base::FilePath::FromUTF8Unsafe(kFilePath),
+      ProvidedFileSystemInterface::OPEN_FILE_MODE_READ,
+      false /* create */,
+      base::Bind(&CallbackLogger::OnOpenFile, callback_logger.GetWeakPtr()));
+  open_file.SetDispatchEventImplForTesting(
+      base::Bind(&LoggingDispatchEventImpl::OnDispatchEventImpl,
+                 base::Unretained(&dispatcher)));
+
+  EXPECT_TRUE(open_file.Execute(kRequestId));
+
+  open_file.OnError(kRequestId, base::File::FILE_ERROR_TOO_MANY_OPENED);
+  ASSERT_EQ(1u, callback_logger.events().size());
+  EXPECT_EQ(base::File::FILE_ERROR_TOO_MANY_OPENED,
+            callback_logger.events()[0]);
+}
+
+}  // namespace operations
+}  // namespace file_system_provider
+}  // namespace chromeos
diff --git a/chrome/browser/chromeos/file_system_provider/provided_file_system.cc b/chrome/browser/chromeos/file_system_provider/provided_file_system.cc
index 7b372f4..72bdac4 100644
--- a/chrome/browser/chromeos/file_system_provider/provided_file_system.cc
+++ b/chrome/browser/chromeos/file_system_provider/provided_file_system.cc
@@ -6,6 +6,7 @@
 
 #include "base/files/file.h"
 #include "chrome/browser/chromeos/file_system_provider/operations/get_metadata.h"
+#include "chrome/browser/chromeos/file_system_provider/operations/open_file.h"
 #include "chrome/browser/chromeos/file_system_provider/operations/read_directory.h"
 #include "chrome/browser/chromeos/file_system_provider/operations/unmount.h"
 #include "chrome/browser/chromeos/file_system_provider/request_manager.h"
@@ -29,9 +30,8 @@ ProvidedFileSystem::~ProvidedFileSystem() {}
 void ProvidedFileSystem::RequestUnmount(
     const fileapi::AsyncFileUtil::StatusCallback& callback) {
   if (!request_manager_.CreateRequest(
-          make_scoped_ptr<RequestManager::HandlerInterface>(
-              new operations::Unmount(
-                  event_router_, file_system_info_, callback)))) {
+          scoped_ptr<RequestManager::HandlerInterface>(new operations::Unmount(
+              event_router_, file_system_info_, callback)))) {
     callback.Run(base::File::FILE_ERROR_SECURITY);
   }
 }
@@ -40,7 +40,7 @@ void ProvidedFileSystem::GetMetadata(
     const base::FilePath& entry_path,
     const fileapi::AsyncFileUtil::GetFileInfoCallback& callback) {
   if (!request_manager_.CreateRequest(
-          make_scoped_ptr<RequestManager::HandlerInterface>(
+          scoped_ptr<RequestManager::HandlerInterface>(
               new operations::GetMetadata(
                   event_router_, file_system_info_, entry_path, callback)))) {
     callback.Run(base::File::FILE_ERROR_SECURITY, base::File::Info());
@@ -50,7 +50,7 @@ void ProvidedFileSystem::GetMetadata(
 void ProvidedFileSystem::ReadDirectory(
     const base::FilePath& directory_path,
     const fileapi::AsyncFileUtil::ReadDirectoryCallback& callback) {
-  if (!request_manager_.CreateRequest(make_scoped_ptr<
+  if (!request_manager_.CreateRequest(scoped_ptr<
           RequestManager::HandlerInterface>(new operations::ReadDirectory(
           event_router_, file_system_info_, directory_path, callback)))) {
     callback.Run(base::File::FILE_ERROR_SECURITY,
@@ -59,6 +59,30 @@ void ProvidedFileSystem::ReadDirectory(
   }
 }
 
+void ProvidedFileSystem::OpenFile(
+    const base::FilePath& file_path,
+    OpenFileMode mode,
+    bool create,
+    const fileapi::AsyncFileUtil::StatusCallback& callback) {
+  // Writing is not supported. Note, that this includes a situation, when a file
+  // exists, but |create| is set to true.
+  if (mode == OPEN_FILE_MODE_WRITE || create) {
+    callback.Run(base::File::FILE_ERROR_SECURITY);
+    return;
+  }
+
+  if (!request_manager_.CreateRequest(
+          scoped_ptr<RequestManager::HandlerInterface>(
+              new operations::OpenFile(event_router_,
+                                       file_system_info_,
+                                       file_path,
+                                       mode,
+                                       create,
+                                       callback)))) {
+    callback.Run(base::File::FILE_ERROR_SECURITY);
+  }
+}
+
 const ProvidedFileSystemInfo& ProvidedFileSystem::GetFileSystemInfo() const {
   return file_system_info_;
 }
diff --git a/chrome/browser/chromeos/file_system_provider/provided_file_system.h b/chrome/browser/chromeos/file_system_provider/provided_file_system.h
index 6fffe4b..4ecc8cb 100644
--- a/chrome/browser/chromeos/file_system_provider/provided_file_system.h
+++ b/chrome/browser/chromeos/file_system_provider/provided_file_system.h
@@ -38,6 +38,11 @@ class ProvidedFileSystem : public ProvidedFileSystemInterface {
   virtual void ReadDirectory(
       const base::FilePath& directory_path,
       const fileapi::AsyncFileUtil::ReadDirectoryCallback& callback) OVERRIDE;
+  virtual void OpenFile(
+      const base::FilePath& file_path,
+      OpenFileMode mode,
+      bool create,
+      const fileapi::AsyncFileUtil::StatusCallback& callback) OVERRIDE;
   virtual const ProvidedFileSystemInfo& GetFileSystemInfo() const OVERRIDE;
   virtual RequestManager* GetRequestManager() OVERRIDE;
 
diff --git a/chrome/browser/chromeos/file_system_provider/provided_file_system_interface.h b/chrome/browser/chromeos/file_system_provider/provided_file_system_interface.h
index 76be11d..126d532 100644
--- a/chrome/browser/chromeos/file_system_provider/provided_file_system_interface.h
+++ b/chrome/browser/chromeos/file_system_provider/provided_file_system_interface.h
@@ -24,6 +24,9 @@ class RequestManager;
 // TODO(mtomasz): Add more methods once implemented.
 class ProvidedFileSystemInterface {
  public:
+  // Mode of opening a file. Used by OpenFile().
+  enum OpenFileMode { OPEN_FILE_MODE_READ, OPEN_FILE_MODE_WRITE };
+
   virtual ~ProvidedFileSystemInterface() {}
 
   // Requests unmounting of the file system. The callback is called when the
@@ -43,6 +46,14 @@ class ProvidedFileSystemInterface {
       const base::FilePath& directory_path,
       const fileapi::AsyncFileUtil::ReadDirectoryCallback& callback) = 0;
 
+  // Requests opening a file at |file_path|. If |create| is set to true, it will
+  // create a file and return succes in case it didn't exist.
+  virtual void OpenFile(
+      const base::FilePath& file_path,
+      OpenFileMode mode,
+      bool create,
+      const fileapi::AsyncFileUtil::StatusCallback& callback) = 0;
+
   // Returns a provided file system info for this file system.
   virtual const ProvidedFileSystemInfo& GetFileSystemInfo() const = 0;
 
diff --git a/chrome/chrome_browser_chromeos.gypi b/chrome/chrome_browser_chromeos.gypi
index cd5c9f0..37097b3 100644
--- a/chrome/chrome_browser_chromeos.gypi
+++ b/chrome/chrome_browser_chromeos.gypi
@@ -382,6 +382,8 @@
         'browser/chromeos/file_system_provider/observer.h',
         'browser/chromeos/file_system_provider/operations/get_metadata.cc',
         'browser/chromeos/file_system_provider/operations/get_metadata.h',
+        'browser/chromeos/file_system_provider/operations/open_file.cc',
+        'browser/chromeos/file_system_provider/operations/open_file.h',
         'browser/chromeos/file_system_provider/operations/operation.cc',
         'browser/chromeos/file_system_provider/operations/operation.h',
         'browser/chromeos/file_system_provider/operations/read_directory.cc',
diff --git a/chrome/chrome_tests_unit.gypi b/chrome/chrome_tests_unit.gypi
index 6f8ace2..d19d1c3 100644
--- a/chrome/chrome_tests_unit.gypi
+++ b/chrome/chrome_tests_unit.gypi
@@ -711,6 +711,7 @@
         'browser/chromeos/file_system_provider/fileapi/provider_async_file_util_unittest.cc',
         'browser/chromeos/file_system_provider/mount_path_util_unittest.cc',
         'browser/chromeos/file_system_provider/operations/get_metadata_unittest.cc',
+        'browser/chromeos/file_system_provider/operations/open_file_unittest.cc',
         'browser/chromeos/file_system_provider/operations/read_directory_unittest.cc',
         'browser/chromeos/file_system_provider/provided_file_system_unittest.cc',
         'browser/chromeos/file_system_provider/request_manager_unittest.cc',
diff --git a/chrome/common/extensions/api/file_system_provider.idl b/chrome/common/extensions/api/file_system_provider.idl
index f8ed6ba..8942bda 100644
--- a/chrome/common/extensions/api/file_system_provider.idl
+++ b/chrome/common/extensions/api/file_system_provider.idl
@@ -29,6 +29,12 @@ namespace fileSystemProvider {
     IO
   };
 
+  // Mode of opening a file. Used by <code>onOpenFileRequested</code>.
+  enum OpenFileMode {
+    READ,
+    WRITE
+  };
+
   // Represents metadata of a file or a directory.
   dictionary EntryMetadata {
     // True if it is a directory.
@@ -116,7 +122,7 @@ namespace fileSystemProvider {
         long fileSystemId,
         DOMString entryPath,
         MetadataCallback successCallback,
-        ErrorCallback errorCallback);
+        ProviderErrorCallback errorCallback);
 
     // Raised when contents of a directory at <code>directoryPath</code> are
     // requested. The results should be returned in chunks by calling the <code>
@@ -126,7 +132,18 @@ namespace fileSystemProvider {
         long fileSystemId,
         DOMString directoryPath,
         EntriesCallback successCallback,
-        ErrorCallback errorCallback);
+        ProviderErrorCallback errorCallback);
+
+    // Raised when opening a file at <code>filePath</code> is requested.
+    // If <code>create</code> is set to <code>true</code> and the file does not
+    // exist, then it should be created.
+    [maxListeners=1] static void onOpenFileRequested(
+        long fileSystemId,
+        DOMString filePath,
+        OpenFileMode mode,
+        boolean create,
+        ProviderSuccessCallback successCallback,
+        ProviderErrorCallback errorCallback);
   };
 };
 
diff --git a/chrome/common/extensions/api/file_system_provider_internal.idl b/chrome/common/extensions/api/file_system_provider_internal.idl
index 7a80d5b..294d09a 100644
--- a/chrome/common/extensions/api/file_system_provider_internal.idl
+++ b/chrome/common/extensions/api/file_system_provider_internal.idl
@@ -48,6 +48,19 @@ namespace fileSystemProviderInternal {
         long fileSystemId,
         long requestId,
         fileSystemProvider.ProviderError error);
+
+    // Internal. Success callback of the <code>onOpenFileRequested</code> event.
+    // Must be called, when opening succeeds.
+    static void openFileRequestedSuccess(
+        long fileSystemId,
+        long requestId);
+
+    // Internal. Error callback of the <code>onOpenFileRequested</code> event.
+    // Must be called when opening fails.
+    static void openFileRequestedError(
+        long fileSystemId,
+        long requestId,
+        fileSystemProvider.ProviderError error);
   };
 };
 
diff --git a/chrome/renderer/resources/extensions/file_system_provider_custom_bindings.js b/chrome/renderer/resources/extensions/file_system_provider_custom_bindings.js
index f59900c..9ea4a01 100644
--- a/chrome/renderer/resources/extensions/file_system_provider_custom_bindings.js
+++ b/chrome/renderer/resources/extensions/file_system_provider_custom_bindings.js
@@ -161,4 +161,24 @@ eventBindings.registerArgumentMassager(
           fileSystemId, directoryPath, onSuccessCallback, onErrorCallback]);
     });
 
+eventBindings.registerArgumentMassager(
+    'fileSystemProvider.onOpenFileRequested',
+    function(args, dispatch) {
+      var fileSystemId = args[0];
+      var requestId = args[1];
+      var filePath = args[2];
+      var mode = args[3];
+      var create = args[4];
+      var onSuccessCallback = function() {
+        fileSystemProviderInternal.openFileRequestedSuccess(
+            fileSystemId, requestId);
+      };
+      var onErrorCallback = function(error) {
+        fileSystemProviderInternal.openFileRequestedError(
+          fileSystemId, requestId, error);
+      }
+      dispatch([fileSystemId, filePath, mode, create, onSuccessCallback,
+                onErrorCallback]);
+    });
+
 exports.binding = binding.generate();