[WIP] Provided file system from NACL.

content/browser/renderer_host/pepper/pepper_filesystem_provider_backend_chromeos.cc

Index: content/browser/renderer_host/pepper/pepper_filesystem_provider_backend_chromeos.cc
diff --git a/content/browser/renderer_host/pepper/pepper_filesystem_provider_backend_chromeos.cc b/content/browser/renderer_host/pepper/pepper_filesystem_provider_backend_chromeos.cc
new file mode 100644
index 0000000000000000000000000000000000000000..28a5f7e9ef43537c4effe3f864ab06350fdc09a7
--- /dev/null
+++ b/content/browser/renderer_host/pepper/pepper_filesystem_provider_backend_chromeos.cc
@@ -0,0 +1,858 @@
+// Copyright 2015 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 "content/browser/renderer_host/pepper/pepper_filesystem_provider_backend_chromeos.h"
+
+#include <chrono>
+
+#include "base/memory/shared_memory.h"
+#include "chrome/browser/chromeos/file_system_provider/provided_file_system_info.h"
+#include "chrome/browser/chromeos/file_system_provider/request_manager.h"
+#include "chrome/browser/chromeos/file_system_provider/service.h"
+#include "chrome/browser/profiles/profile_manager.h"
+#include "content/public/browser/browser_ppapi_host.h"
+#include "content/public/browser/browser_thread.h"
+#include "ppapi/c/pp_errors.h"
+#include "ppapi/host/ppapi_host.h"
+#include "ppapi/proxy/ppapi_messages.h"
+
+using extensions::api::file_system_provider::ProviderError;
+using chromeos::file_system_provider::ProvidedFileSystemInterface;
+using chromeos::file_system_provider::Service;
+using chromeos::file_system_provider::Source_Type;
+using chromeos::PluginEventRouter;
+using content::BrowserThread;
+using ppapi::host::HostMessageContext;
+
+#define MAKE_EVENT_ENTRY(x,handler,operation)\
+  std::pair<std::string,\
+  std::pair<DispatchEventImplCallback,PP_OperationType_Dev>>(\
+  extensions::api::file_system_provider::x::kEventName,\
+  std::pair<DispatchEventImplCallback,PP_OperationType_Dev>(\
+  base::Bind( &PepperFilesystemProviderBackendChromeOS::handler,\
+              weak_factory_.GetWeakPtr() ), operation ) )
+
+namespace content {
+
+namespace {
+
+// TODO(sabin): find a way to get the size of the stream reader internal
+// buffer from the backend
+// Size of the stream reader internal buffer. At most this number of bytes will
+// be read ahead of the requested data.
+const uint32_t kReaderBufferSize = 512 * 1024;  // 512KB.
+
+// Size of the stream writer internal buffer. At most this number of bytes will
+// be postponed for writing.
+const uint32_t kWriterBufferSize = 512 * 1024;  // 512KB.
+
+// The number of requests that can be buffered
+const uint32_t kMaximumCachedReplies = 10;
+
+base::File::Error PP_ProviderErrorToFileError(
+    ProviderError error) {
+  switch (error) {
+    case ProviderError::PROVIDER_ERROR_OK:
+      return base::File::FILE_OK;
+    case ProviderError::PROVIDER_ERROR_FAILED:
+      return base::File::FILE_ERROR_FAILED;
+    case ProviderError::PROVIDER_ERROR_IN_USE:
+      return base::File::FILE_ERROR_IN_USE;
+    case ProviderError::PROVIDER_ERROR_EXISTS:
+      return base::File::FILE_ERROR_EXISTS;
+    case ProviderError::PROVIDER_ERROR_NOT_FOUND:
+      return base::File::FILE_ERROR_NOT_FOUND;
+    case ProviderError::PROVIDER_ERROR_ACCESS_DENIED:
+      return base::File::FILE_ERROR_ACCESS_DENIED;
+    case ProviderError::PROVIDER_ERROR_TOO_MANY_OPENED:
+      return base::File::FILE_ERROR_TOO_MANY_OPENED;
+    case ProviderError::PROVIDER_ERROR_NO_MEMORY:
+      return base::File::FILE_ERROR_NO_MEMORY;
+    case ProviderError::PROVIDER_ERROR_NO_SPACE:
+      return base::File::FILE_ERROR_NO_SPACE;
+    case ProviderError::PROVIDER_ERROR_NOT_A_DIRECTORY:
+      return base::File::FILE_ERROR_NOT_A_DIRECTORY;
+    case ProviderError::PROVIDER_ERROR_INVALID_OPERATION:
+      return base::File::FILE_ERROR_INVALID_OPERATION;
+    case ProviderError::PROVIDER_ERROR_SECURITY:
+      return base::File::FILE_ERROR_SECURITY;
+    case ProviderError::PROVIDER_ERROR_ABORT:
+      return base::File::FILE_ERROR_ABORT;
+    case ProviderError::PROVIDER_ERROR_NOT_A_FILE:
+      return base::File::FILE_ERROR_NOT_A_FILE;
+    case ProviderError::PROVIDER_ERROR_NOT_EMPTY:
+      return base::File::FILE_ERROR_NOT_EMPTY;
+    case ProviderError::PROVIDER_ERROR_INVALID_URL:
+      return base::File::FILE_ERROR_INVALID_URL;
+    case ProviderError::PROVIDER_ERROR_IO:
+      return base::File::FILE_ERROR_IO;
+    case ProviderError::PROVIDER_ERROR_NONE:
+      NOTREACHED();
+  }
+
+  return base::File::FILE_ERROR_FAILED;
+}
+
+} // namespace
+
+PepperFilesystemProviderBackendChromeOS::
+    ProvidedFilesystemInfo::ProvidedFilesystemInfo()
+    :filesystem_id("none"),
+     display_name("none"),
+     plugin_name("none"),
+     writable(false),
+     opened_files_limit(0) {
+}
+PepperFilesystemProviderBackendChromeOS::ShmBuffer::ShmBuffer(
+    uint32_t size, scoped_ptr<base::SharedMemory> shm)
+    : size(size),shm(shm.Pass()) {
+  DCHECK(this->shm);
+}
+
+PepperFilesystemProviderBackendChromeOS::ShmBuffer::~ShmBuffer() {
+
+}
+
+PepperFilesystemProviderBackendChromeOS::
+    ShmChannelSynchronizer::ShmChannelSynchronizer(
+    uint32_t size, FlushRequestCallback callback)
+    : max_size(size),
+    ready(true),
+    callback(callback){
+}
+PepperFilesystemProviderBackendChromeOS::
+    ShmChannelSynchronizer::~ShmChannelSynchronizer() {
+}
+
+bool PepperFilesystemProviderBackendChromeOS::
+    ShmChannelSynchronizer::EnqueueRequest(
+    scoped_ptr<base::ListValue> response) {
+  // If channel ready send it straight away
+  if(ready) {
+    ready = !callback.Run(response.Pass());
+    if(!ready)
+      return true;
+  }
+  // If channel is not ready or failed to send
+  // cache the request
+  if(size() + 1 > max_size)
+    return false;
+  replies.push_back( response.Pass() );
+  return true;
+}
+
+bool PepperFilesystemProviderBackendChromeOS::
+    ShmChannelSynchronizer::PushNextRequest() {
+  // Try and send the request
+  scoped_ptr<base::ListValue> response;
+  while (size()>0 && ready ) {
+    response.reset(replies.front());
+    replies.weak_erase(replies.begin());
+    ready = !callback.Run(response.Pass());
+  }
+  return !ready;
+}
+
+bool
+PepperFilesystemProviderBackendChromeOS::
+    ShmChannelSynchronizer::AckLastPushedRequest() {
+  return ready = true;
+}
+
+uint32_t PepperFilesystemProviderBackendChromeOS::
+    ShmChannelSynchronizer::size() {
+  return replies.size();
+}
+
+
+
+PepperFilesystemProviderBackendChromeOS::
+PepperFilesystemProviderBackendChromeOS(
+    content::BrowserPpapiHost *host,
+    PP_Instance instance,
+    PP_Resource resource)
+         : mounted_(false),
+         host_(host ? host->GetPpapiHost() : nullptr),
+         resource_(resource),
+         write_channel_controller_(new ShmChannelSynchronizer(
+                                kMaximumCachedReplies,
+                                base::Bind(
+                                  &PepperFilesystemProviderBackendChromeOS::
+                                      FlushRequest,
+                                      base::Unretained(this)))),
+         weak_factory_(this) {
+
+  filesystem_info_.plugin_name = std::string("Plugin_") +
+                                 std::to_string(instance);
+
+  std::pair<
+      std::string, std::pair<DispatchEventImplCallback,PP_OperationType_Dev> >
+          ev[] ={
+              MAKE_EVENT_ENTRY(
+                  OnAbortRequested,
+                  SendOperationRequestToPlugin,
+                  PP_OperationType_ABORT),
+              MAKE_EVENT_ENTRY(
+                  OnCloseFileRequested,
+                  SendOperationRequestToPlugin,
+                  PP_OperationType_CLOSEFILE),
+              MAKE_EVENT_ENTRY(
+                  OnCopyEntryRequested,
+                  SendOperationRequestToPlugin,
+                  PP_OperationType_COPYENTRY),
+              MAKE_EVENT_ENTRY(
+                  OnCreateDirectoryRequested,
+                  SendOperationRequestToPlugin,
+                  PP_OperationType_CREATEDIRECTORY),
+              MAKE_EVENT_ENTRY(
+                  OnCreateFileRequested,
+                  SendOperationRequestToPlugin,
+                  PP_OperationType_CREATEFILE),
+              MAKE_EVENT_ENTRY(
+                  OnDeleteEntryRequested,
+                  SendOperationRequestToPlugin,
+                  PP_OperationType_DELETEENTRY),
+              MAKE_EVENT_ENTRY(
+                  OnGetMetadataRequested,
+                  SendOperationRequestToPlugin,
+                  PP_OperationType_GETMETADATA),
+              MAKE_EVENT_ENTRY(
+                  OnMoveEntryRequested,
+                  SendOperationRequestToPlugin,
+                  PP_OperationType_MOVEENTRY),
+              MAKE_EVENT_ENTRY(
+                  OnOpenFileRequested,
+                  SendOperationRequestToPlugin,
+                  PP_OperationType_OPENFILE),
+              MAKE_EVENT_ENTRY(
+                  OnReadDirectoryRequested,
+                  SendOperationRequestToPlugin,
+                  PP_OperationType_READDIRECTORY),
+              MAKE_EVENT_ENTRY(
+                  OnReadFileRequested,
+                  SendOperationRequestToPlugin,
+                  PP_OperationType_READFILE),
+              MAKE_EVENT_ENTRY(
+                  OnTruncateRequested,
+                  SendOperationRequestToPlugin,
+                  PP_OperationType_TRUNCATEENTRY),
+              MAKE_EVENT_ENTRY(
+                  OnUnmountRequested,
+                  SendOperationRequestToPlugin,
+                  PP_OperationType_UNMOUNT),
+              MAKE_EVENT_ENTRY(
+                  OnWriteFileRequested,
+                  SendWriteRequestToPlugin,
+                  PP_OperationType_WRITEFILE)
+  };
+
+  for ( size_t i = 0; i < sizeof( ev ) / sizeof( ev[0] ); ++i ) {
+    handlers_list_.insert( ev[i] );
+    events_.push_back( ev[i].first );
+  }
+}
+
+PepperFilesystemProviderBackendChromeOS::
+~PepperFilesystemProviderBackendChromeOS() {
+  // Unregister the filesystem if state indicates
+  // that we have a mounted filesystem
+  if (mounted_) {
+    // Unregister any registered event from the PluginEventRouter
+    UnregisterFilesystemEventListeners();
+    // Unregister the filesystem backend on the
+    // proper thread from Service
+    BrowserThread::PostTask(
+        BrowserThread::UI,
+        FROM_HERE,
+        base::Bind(
+            base::IgnoreResult(
+                &PepperFilesystemProviderBackendChromeOS::
+                UnregisterFilesystemOnUI),
+            filesystem_info_
+        )
+     );
+  }
+}
+
+// Called when PpapiHostMsg_FilesystemProvider_Mount is received
+// Forwards request to RegisterFilesystemOnUI
+// Response is sent from MountReplyOnIO
+int32_t PepperFilesystemProviderBackendChromeOS::SendMountRequest(
+    ppapi::host::HostMessageContext *context,
+    const base::ListValue& request) {
+
+  base::File::Error status = base::File::FILE_OK;
+  if (mounted_)
+      status = base::File::FILE_ERROR_EXISTS;
+
+  scoped_ptr<MountOperationTranslator> mount_info =
+      MountOperationTranslator::PopulateFromResponse(request);
+  if ( !mount_info.get() )
+    status = base::File::FILE_ERROR_FAILED;
+
+  // Stop and send failure back to the plugin
+  if (status!=base::File::FILE_OK) {
+    MountReplyOnIO(
+        context->MakeReplyMessageContext(),
+        filesystem_info_, base::File::FILE_ERROR_EXISTS);
+    return PP_OK_COMPLETIONPENDING;
+  }
+  // Populate the wanted filesystem configuration
+  ProvidedFilesystemInfo filesystem_info;
+  filesystem_info.plugin_name = filesystem_info_.plugin_name;
+  filesystem_info.filesystem_id = mount_info->file_system_id;
+  filesystem_info.display_name = mount_info->display_name;
+  filesystem_info.writable = mount_info->writable;
+  filesystem_info.opened_files_limit = mount_info->opened_files_limit;
+  // Change thread to create the filesystem backend on the
+  // UI thread. The result of this action is to be interpreted
+  // on the IO thread.
+  BrowserThread::PostTaskAndReplyWithResult(
+      BrowserThread::UI,
+      FROM_HERE,
+      base::Bind(
+          // This creates a filesystem backend owned by the Service
+          // entity
+          &PepperFilesystemProviderBackendChromeOS::RegisterFilesystemOnUI,
+           filesystem_info),
+      // This is called after the above returns to interpret result
+      base::Bind(
+          &PepperFilesystemProviderBackendChromeOS::MountReplyOnIO,
+          weak_factory_.GetWeakPtr(),
+          context->MakeReplyMessageContext(),
+          filesystem_info
+      )
+  );
+  return PP_OK_COMPLETIONPENDING;
+}
+
+// Called when PpapiHostMsg_FilesystemProvider_Unmount is received
+// Forwards request to UnregisterFilesystemOnUI
+// Response is sent from MountReplyOnIO
+int32_t PepperFilesystemProviderBackendChromeOS::SendUnmountRequest(
+    ppapi::host::HostMessageContext *context, std::string fsid) {
+
+  if(!mounted_) {
+    UnmountReplyOnIO(
+        context->MakeReplyMessageContext(),
+        base::File::FILE_ERROR_NOT_FOUND);
+  }
+
+  // Remove registered events from PluginEventRouter
+  UnregisterFilesystemEventListeners();
+
+  BrowserThread::PostTaskAndReplyWithResult(
+      BrowserThread::UI,
+      FROM_HERE,
+      base::Bind(
+          &PepperFilesystemProviderBackendChromeOS::UnregisterFilesystemOnUI,
+          filesystem_info_),
+      base::Bind( &PepperFilesystemProviderBackendChromeOS::UnmountReplyOnIO,
+          weak_factory_.GetWeakPtr(),
+          context->MakeReplyMessageContext())
+  );
+  return PP_OK_COMPLETIONPENDING;
+}
+
+int32_t PepperFilesystemProviderBackendChromeOS::OnPluginResponse(
+    ppapi::host::HostMessageContext* context,
+    const base::ListValue& plugin_response) {
+  scoped_ptr<base::ListValue> response( plugin_response.DeepCopy() );
+  if (!response.get())
+    return PP_ERROR_FAILED;
+  // Remove the custom "header" from the response
+  scoped_ptr<base::Value> operation_value = nullptr;
+  int operation_type = PP_OperationType_NONE;
+  if (!response->Remove(0,&operation_value))
+    return PP_ERROR_FAILED;
+  if (!operation_value->GetAsInteger(&operation_type))
+    return PP_ERROR_FAILED;
+  // Get the status of the operation
+  scoped_ptr<base::Value> status_value=nullptr;
+  bool status = false;
+  if (!response->Remove(0,&status_value))
+    return PP_ERROR_FAILED;
+  if (!status_value->GetAsBoolean(&status))
+    return PP_ERROR_FAILED;
+
+  if ( status ) {// success
+
+    if (operation_type==PP_OperationType_READFILE) { // a preprocess stage
+      AddFromSharedMemoryToMessage(*response);
+      // ACK the receipt and let the plugin know that if it has more
+      // requests it can send them
+      host_->SendUnsolicitedReply(
+          resource_,
+          PpapiPluginMsg_FilesystemProvider_ReadAck()
+      );
+    }
+    BrowserThread::PostTask(
+        BrowserThread::UI,
+        FROM_HERE,
+        base::Bind(
+            base::IgnoreResult(
+                &PepperFilesystemProviderBackendChromeOS::
+                    OnGeneralSuccessResponse),
+            operation_type,
+            filesystem_info_,
+            base::Passed(response.Pass()))
+    );
+  } else { // failure
+    BrowserThread::PostTask(
+        BrowserThread::UI,
+        FROM_HERE,
+        base::Bind(
+            base::IgnoreResult(
+                &PepperFilesystemProviderBackendChromeOS::
+                    OnGeneralErrorResponse),
+            filesystem_info_,
+            base::Passed(response.Pass()))
+    );
+  }
+
+  return PP_OK;
+}
+
+// Sends next cached request if there is any pending
+int32_t PepperFilesystemProviderBackendChromeOS::OnPluginWriteAck(
+    ppapi::host::HostMessageContext* ) {
+  write_channel_controller_->AckLastPushedRequest();
+  write_channel_controller_->PushNextRequest();
+  return PP_OK;
+}
+
+// Add all events to the PluginEventRouter list of dispatchable events
+void PepperFilesystemProviderBackendChromeOS::
+RegisterFilesystemEventListeners() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  PluginEventRouter *router = PluginEventRouter::GetInstance();
+  if (router!=nullptr)
+    router->AddEventsListener( events_, this, filesystem_info_.plugin_name );
+}
+// Remove all events from the PluginEventRouter list of dispatchable events
+void PepperFilesystemProviderBackendChromeOS::
+UnregisterFilesystemEventListeners() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  PluginEventRouter *router = PluginEventRouter::GetInstance();
+  if (router!=nullptr)
+    router->RemoveEventsListeners( events_, this, filesystem_info_.plugin_name);
+}
+
+// Static
+// Responsible with the creations and registration of a new provided filesystem
+base::File::Error PepperFilesystemProviderBackendChromeOS::
+RegisterFilesystemOnUI(
+    ProvidedFilesystemInfo filesystem_info)
+{
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
+  Service *fs_service = Service::Get(ProfileManager::GetActiveUserProfile());
+  DCHECK(fs_service);
+
+  chromeos::file_system_provider::MountOptions options(
+      filesystem_info.filesystem_id, filesystem_info.display_name);
+
+  options.writable = filesystem_info.writable;
+  options.opened_files_limit = filesystem_info.opened_files_limit;
+  options.supports_notify_tag = false; // Check this
+
+  base::File::Error error = fs_service->MountFileSystem(
+      filesystem_info.plugin_name,
+      options,
+      Source_Type::plugin );
+
+  return error; // This will be interpreted by MountReplyOnIO
+}
+
+// Sends feedback to the plugin
+// and sets state
+void PepperFilesystemProviderBackendChromeOS::MountReplyOnIO(
+    ppapi::host::ReplyMessageContext reply_msg,
+    ProvidedFilesystemInfo filesystem_info,
+    base::File::Error err) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  // Do not register and send error back
+  if ( err != base::File::FILE_OK ) {
+    reply_msg.params.set_result(PP_OK);
+    host_->SendReply(
+        reply_msg,
+        PpapiPluginMsg_FilesystemProvider_MountReply( PP_ProviderError_FAILED )
+    );
+    return;
+  }
+
+  filesystem_info_.writable = filesystem_info.writable;
+  filesystem_info_.opened_files_limit = filesystem_info.opened_files_limit;
+  filesystem_info_.filesystem_id = filesystem_info.filesystem_id;
+  filesystem_info_.display_name  = filesystem_info.display_name;
+  mounted_ = true;
+
+  // Initialize the shared memory buffers if needed
+  if (!read_write_buffer_.get())
+    InitializeMemoryBuffer();
+  RegisterFilesystemEventListeners();
+
+  reply_msg.params.set_result(PP_OK);
+  host_->SendReply(
+      reply_msg,
+      PpapiPluginMsg_FilesystemProvider_MountReply( PP_ProviderError_OK )
+  );
+}
+
+//static
+// Responsible with removal of the filesystem backend
+base::File::Error PepperFilesystemProviderBackendChromeOS::
+UnregisterFilesystemOnUI(
+    ProvidedFilesystemInfo filesystem_info) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
+  Service *fs_service = Service::Get(ProfileManager::GetActiveUserProfile());
+  DCHECK(fs_service);
+
+  base::File::Error err = fs_service->UnmountFileSystem(
+      filesystem_info.plugin_name,
+      filesystem_info.filesystem_id,
+      chromeos::file_system_provider::Service::UNMOUNT_REASON_USER );
+
+  return err;
+}
+
+// Sends feedback to the plugin
+// and resets state
+void PepperFilesystemProviderBackendChromeOS::UnmountReplyOnIO(
+    ppapi::host::ReplyMessageContext reply_msg, base::File::Error err) {
+
+  reply_msg.params.set_result(PP_OK);
+  // Unregister all events
+  UnregisterFilesystemEventListeners();
+
+  mounted_ = false;
+  filesystem_info_.writable = false;
+  filesystem_info_.opened_files_limit = 0;
+  filesystem_info_.filesystem_id = "";
+  filesystem_info_.display_name = "";
+
+  // Send result to the plugin
+  host_->SendReply(
+      reply_msg,
+      PpapiPluginMsg_FilesystemProvider_MountReply( PP_ProviderError_OK )
+  );
+}
+
+// Handle events that are dispatched by the PluginEventRouter
+void PepperFilesystemProviderBackendChromeOS::OnDispatchEvent(
+    std::string event_name, scoped_ptr<base::ListValue> event_args) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  ListOfHandlersIterator it = handlers_list_.find( event_name );
+  if ( it != handlers_list_.end() )
+    it->second.first.Run( it->second.second, event_args.Pass() );
+}
+
+// Sends requests to plugin
+void PepperFilesystemProviderBackendChromeOS::SendOperationRequestToPlugin(
+    PP_OperationType_Dev operation_type,
+    scoped_ptr<base::ListValue> event_args) {
+
+  //TODO(sabin): Remove this when done testing
+  if(operation_type==PP_OperationType_OPENFILE)
+    time_stamp_=std::chrono::system_clock::now();
+  else if(operation_type==PP_OperationType_CLOSEFILE) {
+    std::chrono::duration<double> elapsed_seconds =
+        std::chrono::system_clock::now()-time_stamp_;
+    LOG(ERROR) <<"Read/Write operation time: "<< elapsed_seconds.count()<<
+                 " seconds";
+  }
+
+  host_->SendUnsolicitedReply(
+      resource_,
+      PpapiPluginMsg_FilesystemProvider_OperationRequest(
+          operation_type,
+          *event_args)
+  );
+
+}
+
+void PepperFilesystemProviderBackendChromeOS::SendWriteRequestToPlugin(
+    PP_OperationType_Dev operation_type,
+    scoped_ptr<base::ListValue> request) {
+  // Handle write to filesystem
+  // Put the chunk into the shared memory buffer or cache it
+  // if channel is not free
+  // TODO(sabin): Send error back to backend if this fails
+  write_channel_controller_->EnqueueRequest(request.Pass());
+}
+
+// Transforms messages that are received from
+// the plugin in response of filesystem operations and sends
+// them back to the filesystem backend.
+int32_t PepperFilesystemProviderBackendChromeOS::OnGeneralSuccessResponse(
+    int operation,
+    ProvidedFilesystemInfo filesystem_info,
+    scoped_ptr<base::ListValue> args) {
+
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  Service *fs_service = Service::Get(ProfileManager::GetActiveUserProfile());
+  DCHECK(fs_service);
+
+  ProvidedFileSystemInterface* fs_interface =
+      fs_service->GetProvidedFileSystem(
+          filesystem_info.plugin_name,
+          filesystem_info.filesystem_id);
+
+  if (fs_interface==nullptr)
+    return PP_ERROR_FAILED;
+
+  switch(operation) {
+    case PP_OperationType_READDIRECTORY: {
+        using extensions::api::
+              file_system_provider_internal::ReadDirectoryRequestedSuccess::
+                  Params;
+        scoped_ptr<Params> params(Params::Create(*args));
+        if(!params.get())
+          return PP_ERROR_FAILED;
+
+        const bool has_more = params->has_more;
+        if ( base::File::FILE_OK!=
+             fs_interface->GetRequestManager()->FulfillRequest(
+                params->request_id,
+                chromeos::file_system_provider::RequestValue::
+                    CreateForReadDirectorySuccess(params.Pass()),
+                has_more)
+        )
+          return PP_ERROR_FAILED;
+    }
+    break;
+    case PP_OperationType_GETMETADATA: {
+        using extensions::api::file_system_provider_internal::
+        GetMetadataRequestedSuccess::Params;
+        scoped_ptr<Params> params(Params::Create(*args));
+        if(!params.get())
+          return PP_ERROR_FAILED;
+
+        if (base::File::FILE_OK!=
+            fs_interface->GetRequestManager()->FulfillRequest(
+                params->request_id,
+                chromeos::file_system_provider::RequestValue::
+                    CreateForGetMetadataSuccess(params.Pass()),
+                false)
+        )
+          return PP_ERROR_FAILED;
+    }
+    break;
+    case PP_OperationType_READFILE: {
+        using extensions::api::file_system_provider_internal::
+        ReadFileRequestedSuccess::Params;
+        scoped_ptr<Params> params(Params::Create(*args));
+        if (!params.get())
+          return PP_ERROR_FAILED;
+
+        const bool has_more = params->has_more;
+        if (base::File::FILE_OK!=
+            fs_interface->GetRequestManager()->FulfillRequest(
+                params->request_id,
+                chromeos::file_system_provider::RequestValue::
+                    CreateForReadFileSuccess(params.Pass()),
+                has_more) )
+          return PP_ERROR_FAILED;
+    }
+    break;
+    case PP_OperationType_UNMOUNT: {
+        using extensions::api::file_system_provider_internal::
+        UnmountRequestedSuccess::Params;
+        scoped_ptr<Params> params(Params::Create(*args));
+        if(!params.get())
+          return PP_ERROR_FAILED;
+
+        if (base::File::FILE_OK!=
+            fs_service->UnmountFileSystem(
+                filesystem_info.plugin_name, filesystem_info.filesystem_id,
+                chromeos::file_system_provider::Service::UNMOUNT_REASON_USER)
+         )
+           return PP_ERROR_FAILED;
+    }
+    break;
+    default: {
+        using extensions::api::file_system_provider_internal::
+        OperationRequestedSuccess::Params;
+        scoped_ptr<Params> params(Params::Create(*args));
+        if(!params.get())
+          return PP_ERROR_FAILED;
+
+        if (base::File::FILE_OK!=
+            fs_interface->GetRequestManager()->FulfillRequest(
+                params->request_id,
+                chromeos::file_system_provider::RequestValue::
+                    CreateForOperationSuccess(params.Pass()),
+                false)
+           )
+          return PP_ERROR_FAILED;
+    }
+    break;
+  }
+  return PP_OK;
+}
+
+int32_t PepperFilesystemProviderBackendChromeOS::OnGeneralErrorResponse(
+    ProvidedFilesystemInfo filesystem_info,
+    scoped_ptr<base::ListValue> args) {
+
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  Service *fs_service = Service::Get(ProfileManager::GetActiveUserProfile());
+  DCHECK(fs_service);
+
+  ProvidedFileSystemInterface* fs_interface =
+      fs_service->GetProvidedFileSystem(
+          filesystem_info.plugin_name,
+          filesystem_info.filesystem_id);
+  if(fs_interface==nullptr)
+    return PP_ERROR_FAILED;
+
+  using extensions::api::file_system_provider_internal::
+      OperationRequestedError::Params;
+  scoped_ptr<Params> params(Params::Create(*args));
+  if(!params.get())
+    return PP_ERROR_FAILED;
+
+  const base::File::Error error = PP_ProviderErrorToFileError(params->error);
+
+   if( base::File::FILE_OK!=
+       fs_interface->GetRequestManager()->RejectRequest(
+           params->request_id,
+           chromeos::file_system_provider::RequestValue::
+               CreateForOperationError(params.Pass()),
+           error)
+     )
+     return PP_ERROR_FAILED;
+   return PP_OK;
+}
+
+bool PepperFilesystemProviderBackendChromeOS::FlushRequest(
+    scoped_ptr<base::ListValue> request) {
+  if(!request.get())
+    return false;
+
+  if(!AddFromMessageToSharedMemory(*request))
+    return false;
+
+  host_->SendUnsolicitedReply(
+      resource_,
+      PpapiPluginMsg_FilesystemProvider_OperationRequest(
+          PP_OperationType_WRITEFILE,
+          *request));
+  return true;
+}
+
+bool PepperFilesystemProviderBackendChromeOS::InitializeMemoryBuffer() {
+  // Already initialized
+  if(read_write_buffer_.get())
+    return false;
+  scoped_ptr<base::SharedMemory> buffer( new base::SharedMemory );
+  size_t size = kReaderBufferSize + kWriterBufferSize;
+  if (!buffer.get() ||
+      !buffer->CreateAndMapAnonymous(size))
+    return false;
+  read_write_buffer_=make_scoped_ptr(new ShmBuffer(size, buffer.Pass()));
+  if(!read_write_buffer_.get())
+      return false;
+  using ppapi::proxy::SerializedHandle;
+  std::vector<SerializedHandle> handles;
+  handles.push_back(
+        SerializedHandle(read_write_buffer_->shm->handle(), size ));
+  // Send a message to the plugin with the shared mem handle
+  host_->SendUnsolicitedReplyWithHandles(
+      resource_,
+      PpapiPluginMsg_FilesystemProvider_Buffers(
+          kReaderBufferSize,
+          kWriterBufferSize),
+      handles
+      );
+  return true;
+}
+bool PepperFilesystemProviderBackendChromeOS::AddFromSharedMemoryToMessage(
+    base::ListValue& message) {
+  DCHECK(read_write_buffer_.get());
+  double out = 0;
+  if(!message.GetDouble(2,&out))
+    return false;
+  size_t out_size = out;
+  if(out_size>kReaderBufferSize)
+    return false;
+
+  // Replace the size with the actual data
+  return message.Set(2, base::BinaryValue::CreateWithCopiedBuffer(
+        (const char*)read_write_buffer_->shm->memory(), out_size));
+}
+
+bool PepperFilesystemProviderBackendChromeOS::AddFromMessageToSharedMemory(
+    base::ListValue& message) {
+  if( !read_write_buffer_.get() )
+    return false;
+
+  base::Value *dict_value = nullptr;
+  if(!message.Get(0,&dict_value))
+    return false;
+
+  base::DictionaryValue* dict =
+      static_cast<base::DictionaryValue*>(dict_value);
+  const base::BinaryValue* binary_value = NULL;
+  if (!dict->GetBinary("data", &binary_value))
+    return false;
+  // This can be '0'
+  size_t binary_size =binary_value->GetSize();
+  // Skip the read buffer and copy to shared mem the buffer into
+  // the write portion of the buffer
+  if(binary_size>kWriterBufferSize)
+    return false;
+  memcpy( (char*)read_write_buffer_->shm->memory()+kReaderBufferSize,
+          binary_value->GetBuffer(),
+          binary_size);
+  dict->Remove( "data", nullptr );
+  dict->SetDouble( "size",binary_size);
+  return true;
+}
+
+scoped_ptr<MountOperationTranslator>
+    MountOperationTranslator::PopulateFromResponse(
+        const base::ListValue& request) {
+  const base::Value *dict_value = nullptr;
+  if(!request.Get(0,&dict_value))
+    return scoped_ptr<MountOperationTranslator>();
+
+  const base::DictionaryValue* dict =
+      static_cast<const base::DictionaryValue*>(dict_value);
+
+  scoped_ptr< MountOperationTranslator > out(new MountOperationTranslator);
+
+  const base::Value* data_value = nullptr;
+  if (!dict->GetWithoutPathExpansion("fileSystemId", &data_value) ||
+      !data_value->IsType(base::Value::TYPE_STRING))
+    return scoped_ptr<MountOperationTranslator>();
+  if (!data_value->GetAsString(&out->file_system_id))
+    return scoped_ptr<MountOperationTranslator>();
+  if (!dict->GetWithoutPathExpansion("displayName", &data_value) ||
+      !data_value->IsType(base::Value::TYPE_STRING))
+    return scoped_ptr<MountOperationTranslator>();
+  if (!data_value->GetAsString(&out->display_name))
+    return scoped_ptr<MountOperationTranslator>();
+  if (!dict->GetWithoutPathExpansion("writable", &data_value) ||
+      !data_value->IsType(base::Value::TYPE_BOOLEAN))
+    return scoped_ptr<MountOperationTranslator>();
+  if (!data_value->GetAsBoolean(&out->writable))
+    return scoped_ptr<MountOperationTranslator>();
+
+  if (!dict->GetWithoutPathExpansion("openedFilesLimit", &data_value) ||
+      !data_value->IsType(base::Value::TYPE_INTEGER))
+    return scoped_ptr<MountOperationTranslator>();
+  if (!data_value->GetAsInteger(&out->opened_files_limit))
+    return scoped_ptr<MountOperationTranslator>();
+
+  return out.Pass();
+}
+
+}// namespace content
+