path: root/extensions/browser/api/printer_provider/printer_provider_api.cc

// 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 "extensions/browser/api/printer_provider/printer_provider_api.h"

#include <map>
#include <set>
#include <utility>
#include <vector>

#include "base/bind.h"
#include "base/i18n/rtl.h"
#include "base/json/json_string_value_serializer.h"
#include "base/macros.h"
#include "base/scoped_observer.h"
#include "base/strings/string16.h"
#include "base/strings/utf_string_conversions.h"
#include "base/values.h"
#include "device/usb/usb_device.h"
#include "extensions/browser/api/printer_provider/printer_provider_print_job.h"
#include "extensions/browser/api/printer_provider_internal/printer_provider_internal_api.h"
#include "extensions/browser/api/printer_provider_internal/printer_provider_internal_api_observer.h"
#include "extensions/browser/api/usb/usb_guid_map.h"
#include "extensions/browser/event_router.h"
#include "extensions/browser/extension_registry.h"
#include "extensions/browser/extension_registry_observer.h"
#include "extensions/common/api/printer_provider.h"
#include "extensions/common/api/printer_provider_internal.h"
#include "extensions/common/api/usb.h"
#include "extensions/common/extension.h"

using device::UsbDevice;

namespace extensions {

namespace {

// The separator between extension id and the extension's internal printer id
// used when generating a printer id unique across extensions.
const char kPrinterIdSeparator = ':';

// Given an extension ID and an ID of a printer reported by the extension, it
// generates a ID for the printer unique across extensions (assuming that the
// printer id is unique in the extension's space).
std::string GeneratePrinterId(const std::string& extension_id,
                              const std::string& internal_printer_id) {
  std::string result = extension_id;
  result.append(1, kPrinterIdSeparator);
  result.append(internal_printer_id);
  return result;
}

// Parses an ID created using |GeneratePrinterId| to it's components:
// the extension ID and the printer ID internal to the extension.
// Returns whenter the ID was succesfully parsed.
bool ParsePrinterId(const std::string& printer_id,
                    std::string* extension_id,
                    std::string* internal_printer_id) {
  size_t separator = printer_id.find_first_of(kPrinterIdSeparator);
  if (separator == std::string::npos)
    return false;
  *extension_id = printer_id.substr(0, separator);
  *internal_printer_id = printer_id.substr(separator + 1);
  return true;
}

void UpdatePrinterWithExtensionInfo(base::DictionaryValue* printer,
                                    const Extension* extension) {
  std::string internal_printer_id;
  CHECK(printer->GetString("id", &internal_printer_id));
  printer->SetString("id",
                     GeneratePrinterId(extension->id(), internal_printer_id));
  printer->SetString("extensionId", extension->id());
  printer->SetString("extensionName", extension->name());

  base::string16 printer_name;
  if (printer->GetString("name", &printer_name) &&
      base::i18n::AdjustStringForLocaleDirection(&printer_name)) {
    printer->SetString("name", printer_name);
  }

  base::string16 printer_description;
  if (printer->GetString("description", &printer_description) &&
      base::i18n::AdjustStringForLocaleDirection(&printer_description)) {
    printer->SetString("description", printer_description);
  }
}

// Holds information about a pending onGetPrintersRequested request;
// in particular, the list of extensions to which the event was dispatched but
// which haven't yet responded, and the |GetPrinters| callback associated with
// the event.
class GetPrintersRequest {
 public:
  explicit GetPrintersRequest(
      const PrinterProviderAPI::GetPrintersCallback& callback);
  ~GetPrintersRequest();

  // Adds an extension id to the list of the extensions that need to respond
  // to the event.
  void AddSource(const std::string& extension_id);

  // Whether all extensions have responded to the event.
  bool IsDone() const;

  // Runs the callback for an extension and removes the extension from the
  // list of extensions that still have to respond to the event.
  void ReportForExtension(const std::string& extension_id,
                          const base::ListValue& printers);

 private:
  // Callback reporting event result for an extension. Called once for each
  // extension.
  PrinterProviderAPI::GetPrintersCallback callback_;

  // The list of extensions that still have to respond to the event.
  std::set<std::string> extensions_;
};

// Keeps track of pending chrome.printerProvider.onGetPrintersRequested
// requests.
class PendingGetPrintersRequests {
 public:
  PendingGetPrintersRequests();
  ~PendingGetPrintersRequests();

  // Adds a new request to the set of pending requests. Returns the id
  // assigned to the request.
  int Add(const PrinterProviderAPI::GetPrintersCallback& callback);

  // Completes a request for an extension. It runs the request callback with
  // values reported by the extension.
  bool CompleteForExtension(const std::string& extension_id,
                            int request_id,
                            const base::ListValue& result);

  // Runs callbacks for the extension for all requests that are waiting for a
  // response from the extension with the provided extension id. Callbacks are
  // called as if the extension reported empty set of printers.
  void FailAllForExtension(const std::string& extension_id);

  // Adds an extension id to the list of the extensions that need to respond to
  // the event.
  bool AddSource(int request_id, const std::string& extension_id);

 private:
  int last_request_id_;
  std::map<int, GetPrintersRequest> pending_requests_;

  DISALLOW_COPY_AND_ASSIGN(PendingGetPrintersRequests);
};

// Keeps track of pending chrome.printerProvider.onGetCapabilityRequested
// requests for an extension.
class PendingGetCapabilityRequests {
 public:
  PendingGetCapabilityRequests();
  ~PendingGetCapabilityRequests();

  // Adds a new request to the set. Only information needed is the callback
  // associated with the request. Returns the id assigned to the request.
  int Add(const PrinterProviderAPI::GetCapabilityCallback& callback);

  // Completes the request with the provided request id. It runs the request
  // callback and removes the request from the set.
  bool Complete(int request_id, const base::DictionaryValue& result);

  // Runs all pending callbacks with empty capability value and clears the
  // set of pending requests.
  void FailAll();

 private:
  int last_request_id_;
  std::map<int, PrinterProviderAPI::GetCapabilityCallback> pending_requests_;
};

// Keeps track of pending chrome.printerProvider.onPrintRequested requests
// for an extension.
class PendingPrintRequests {
 public:
  PendingPrintRequests();
  ~PendingPrintRequests();

  // Adds a new request to the set. Only information needed is the callback
  // associated with the request. Returns the id assigned to the request.
  int Add(const PrinterProviderPrintJob& job,
          const PrinterProviderAPI::PrintCallback& callback);

  // Gets print job associated with a request.
  const PrinterProviderPrintJob* GetPrintJob(int request_id) const;

  // Completes the request with the provided request id. It runs the request
  // callback and removes the request from the set.
  bool Complete(int request_id, bool success, const std::string& result);

  // Runs all pending callbacks with ERROR_FAILED and clears the set of
  // pending requests.
  void FailAll();

 private:
  struct PrintRequest {
    PrinterProviderAPI::PrintCallback callback;
    PrinterProviderPrintJob job;
  };

  int last_request_id_;
  std::map<int, PrintRequest> pending_requests_;
};

// Keeps track of pending chrome.printerProvider.onGetUsbPrinterInfoRequested
// requests for an extension.
class PendingUsbPrinterInfoRequests {
 public:
  PendingUsbPrinterInfoRequests();
  ~PendingUsbPrinterInfoRequests();

  // Adds a new request to the set. Only information needed is the callback
  // associated with the request. Returns the id assigned to the request.
  int Add(const PrinterProviderAPI::GetPrinterInfoCallback& callback);

  // Completes the request with the provided request id. It runs the request
  // callback and removes the request from the set.
  void Complete(int request_id, const base::DictionaryValue& printer_info);

  // Runs all pending callbacks with empty capability value and clears the
  // set of pending requests.
  void FailAll();

 private:
  int last_request_id_ = 0;
  std::map<int, PrinterProviderAPI::GetPrinterInfoCallback> pending_requests_;
};

// Implements chrome.printerProvider API events.
class PrinterProviderAPIImpl : public PrinterProviderAPI,
                               public PrinterProviderInternalAPIObserver,
                               public ExtensionRegistryObserver {
 public:
  explicit PrinterProviderAPIImpl(content::BrowserContext* browser_context);
  ~PrinterProviderAPIImpl() override;

 private:
  // PrinterProviderAPI implementation:
  void DispatchGetPrintersRequested(
      const PrinterProviderAPI::GetPrintersCallback& callback) override;
  void DispatchGetCapabilityRequested(
      const std::string& printer_id,
      const PrinterProviderAPI::GetCapabilityCallback& callback) override;
  void DispatchPrintRequested(
      const PrinterProviderPrintJob& job,
      const PrinterProviderAPI::PrintCallback& callback) override;
  const PrinterProviderPrintJob* GetPrintJob(const Extension* extension,
                                             int request_id) const override;
  void DispatchGetUsbPrinterInfoRequested(
      const std::string& extension_id,
      scoped_refptr<UsbDevice> device,
      const PrinterProviderAPI::GetPrinterInfoCallback& callback) override;

  // PrinterProviderInternalAPIObserver implementation:
  void OnGetPrintersResult(
      const Extension* extension,
      int request_id,
      const PrinterProviderInternalAPIObserver::PrinterInfoVector& result)
      override;
  void OnGetCapabilityResult(const Extension* extension,
                             int request_id,
                             const base::DictionaryValue& result) override;
  void OnPrintResult(const Extension* extension,
                     int request_id,
                     api::printer_provider_internal::PrintError error) override;
  void OnGetUsbPrinterInfoResult(
      const Extension* extension,
      int request_id,
      const api::printer_provider::PrinterInfo* printer_info) override;

  // ExtensionRegistryObserver implementation:
  void OnExtensionUnloaded(content::BrowserContext* browser_context,
                           const Extension* extension,
                           UnloadedExtensionInfo::Reason reason) override;

  // Called before chrome.printerProvider.onGetPrintersRequested event is
  // dispatched to an extension. It returns whether the extension is interested
  // in the event. If the extension listens to the event, it's added to the set
  // of |request| sources. |request| is |GetPrintersRequest| object associated
  // with the event.
  bool WillRequestPrinters(int request_id,
                           content::BrowserContext* browser_context,
                           const Extension* extension,
                           Event* event,
                           const base::DictionaryValue* listener_filter);

  content::BrowserContext* browser_context_;

  PendingGetPrintersRequests pending_get_printers_requests_;

  std::map<std::string, PendingPrintRequests> pending_print_requests_;

  std::map<std::string, PendingGetCapabilityRequests>
      pending_capability_requests_;

  std::map<std::string, PendingUsbPrinterInfoRequests>
      pending_usb_printer_info_requests_;

  ScopedObserver<PrinterProviderInternalAPI, PrinterProviderInternalAPIObserver>
      internal_api_observer_;

  ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
      extension_registry_observer_;

  DISALLOW_COPY_AND_ASSIGN(PrinterProviderAPIImpl);
};

GetPrintersRequest::GetPrintersRequest(
    const PrinterProviderAPI::GetPrintersCallback& callback)
    : callback_(callback) {
}

GetPrintersRequest::~GetPrintersRequest() {
}

void GetPrintersRequest::AddSource(const std::string& extension_id) {
  extensions_.insert(extension_id);
}

bool GetPrintersRequest::IsDone() const {
  return extensions_.empty();
}

void GetPrintersRequest::ReportForExtension(const std::string& extension_id,
                                            const base::ListValue& printers) {
  if (extensions_.erase(extension_id) > 0)
    callback_.Run(printers, IsDone());
}

PendingGetPrintersRequests::PendingGetPrintersRequests() : last_request_id_(0) {
}

PendingGetPrintersRequests::~PendingGetPrintersRequests() {
}

int PendingGetPrintersRequests::Add(
    const PrinterProviderAPI::GetPrintersCallback& callback) {
  pending_requests_.insert(
      std::make_pair(++last_request_id_, GetPrintersRequest(callback)));
  return last_request_id_;
}

bool PendingGetPrintersRequests::CompleteForExtension(
    const std::string& extension_id,
    int request_id,
    const base::ListValue& result) {
  auto it = pending_requests_.find(request_id);
  if (it == pending_requests_.end())
    return false;

  it->second.ReportForExtension(extension_id, result);
  if (it->second.IsDone()) {
    pending_requests_.erase(it);
  }
  return true;
}

void PendingGetPrintersRequests::FailAllForExtension(
    const std::string& extension_id) {
  auto it = pending_requests_.begin();
  while (it != pending_requests_.end()) {
    int request_id = it->first;
    // |it| may get deleted during |CompleteForExtension|, so progress it to the
    // next item before calling the method.
    ++it;
    CompleteForExtension(extension_id, request_id, base::ListValue());
  }
}

bool PendingGetPrintersRequests::AddSource(int request_id,
                                           const std::string& extension_id) {
  auto it = pending_requests_.find(request_id);
  if (it == pending_requests_.end())
    return false;

  it->second.AddSource(extension_id);
  return true;
}

PendingGetCapabilityRequests::PendingGetCapabilityRequests()
    : last_request_id_(0) {
}

PendingGetCapabilityRequests::~PendingGetCapabilityRequests() {
}

int PendingGetCapabilityRequests::Add(
    const PrinterProviderAPI::GetCapabilityCallback& callback) {
  pending_requests_[++last_request_id_] = callback;
  return last_request_id_;
}

bool PendingGetCapabilityRequests::Complete(
    int request_id,
    const base::DictionaryValue& response) {
  auto it = pending_requests_.find(request_id);
  if (it == pending_requests_.end())
    return false;

  PrinterProviderAPI::GetCapabilityCallback callback = it->second;
  pending_requests_.erase(it);

  callback.Run(response);
  return true;
}

void PendingGetCapabilityRequests::FailAll() {
  for (auto& request : pending_requests_)
    request.second.Run(base::DictionaryValue());
  pending_requests_.clear();
}

PendingPrintRequests::PendingPrintRequests() : last_request_id_(0) {
}

PendingPrintRequests::~PendingPrintRequests() {
}

int PendingPrintRequests::Add(
    const PrinterProviderPrintJob& job,
    const PrinterProviderAPI::PrintCallback& callback) {
  PrintRequest request;
  request.callback = callback;
  request.job = job;
  pending_requests_[++last_request_id_] = request;
  return last_request_id_;
}

bool PendingPrintRequests::Complete(int request_id,
                                    bool success,
                                    const std::string& response) {
  auto it = pending_requests_.find(request_id);
  if (it == pending_requests_.end())
    return false;

  PrinterProviderAPI::PrintCallback callback = it->second.callback;
  pending_requests_.erase(it);

  callback.Run(success, response);
  return true;
}

const PrinterProviderPrintJob* PendingPrintRequests::GetPrintJob(
    int request_id) const {
  auto it = pending_requests_.find(request_id);
  if (it == pending_requests_.end())
    return nullptr;

  return &it->second.job;
}

void PendingPrintRequests::FailAll() {
  for (auto& request : pending_requests_)
    request.second.callback.Run(false,
                                PrinterProviderAPI::GetDefaultPrintError());
  pending_requests_.clear();
}

PendingUsbPrinterInfoRequests::PendingUsbPrinterInfoRequests() {
}

PendingUsbPrinterInfoRequests::~PendingUsbPrinterInfoRequests() {
}

int PendingUsbPrinterInfoRequests::Add(
    const PrinterProviderAPI::GetPrinterInfoCallback& callback) {
  pending_requests_[++last_request_id_] = callback;
  return last_request_id_;
}

void PendingUsbPrinterInfoRequests::Complete(
    int request_id,
    const base::DictionaryValue& printer_info) {
  auto it = pending_requests_.find(request_id);
  if (it == pending_requests_.end())
    return;

  PrinterProviderAPI::GetPrinterInfoCallback callback = it->second;
  pending_requests_.erase(it);

  callback.Run(printer_info);
}

void PendingUsbPrinterInfoRequests::FailAll() {
  for (auto& request : pending_requests_) {
    request.second.Run(base::DictionaryValue());
  }
  pending_requests_.clear();
}

PrinterProviderAPIImpl::PrinterProviderAPIImpl(
    content::BrowserContext* browser_context)
    : browser_context_(browser_context),
      internal_api_observer_(this),
      extension_registry_observer_(this) {
  internal_api_observer_.Add(
      PrinterProviderInternalAPI::GetFactoryInstance()->Get(browser_context));
  extension_registry_observer_.Add(ExtensionRegistry::Get(browser_context));
}

PrinterProviderAPIImpl::~PrinterProviderAPIImpl() {
}

void PrinterProviderAPIImpl::DispatchGetPrintersRequested(
    const GetPrintersCallback& callback) {
  EventRouter* event_router = EventRouter::Get(browser_context_);
  if (!event_router->HasEventListener(
          api::printer_provider::OnGetPrintersRequested::kEventName)) {
    callback.Run(base::ListValue(), true /* done */);
    return;
  }

  // |pending_get_printers_requests_| take ownership of |request| which gets
  // NULLed out. Save the pointer before passing it to the requests, as it will
  // be needed later on.
  int request_id = pending_get_printers_requests_.Add(callback);

  scoped_ptr<base::ListValue> internal_args(new base::ListValue);
  // Request id is not part of the public API, but it will be massaged out in
  // custom bindings.
  internal_args->AppendInteger(request_id);

  scoped_ptr<Event> event(
      new Event(events::PRINTER_PROVIDER_ON_GET_PRINTERS_REQUESTED,
                api::printer_provider::OnGetPrintersRequested::kEventName,
                internal_args.Pass()));
  // This callback is called synchronously during |BroadcastEvent|, so
  // Unretained is safe.
  event->will_dispatch_callback =
      base::Bind(&PrinterProviderAPIImpl::WillRequestPrinters,
                 base::Unretained(this), request_id);

  event_router->BroadcastEvent(event.Pass());
}

void PrinterProviderAPIImpl::DispatchGetCapabilityRequested(
    const std::string& printer_id,
    const PrinterProviderAPI::GetCapabilityCallback& callback) {
  std::string extension_id;
  std::string internal_printer_id;
  if (!ParsePrinterId(printer_id, &extension_id, &internal_printer_id)) {
    callback.Run(base::DictionaryValue());
    return;
  }

  EventRouter* event_router = EventRouter::Get(browser_context_);
  if (!event_router->ExtensionHasEventListener(
          extension_id,
          api::printer_provider::OnGetCapabilityRequested::kEventName)) {
    callback.Run(base::DictionaryValue());
    return;
  }

  int request_id = pending_capability_requests_[extension_id].Add(callback);

  scoped_ptr<base::ListValue> internal_args(new base::ListValue);
  // Request id is not part of the public API, but it will be massaged out in
  // custom bindings.
  internal_args->AppendInteger(request_id);
  internal_args->AppendString(internal_printer_id);

  scoped_ptr<Event> event(
      new Event(events::PRINTER_PROVIDER_ON_GET_CAPABILITY_REQUESTED,
                api::printer_provider::OnGetCapabilityRequested::kEventName,
                internal_args.Pass()));

  event_router->DispatchEventToExtension(extension_id, event.Pass());
}

void PrinterProviderAPIImpl::DispatchPrintRequested(
    const PrinterProviderPrintJob& job,
    const PrinterProviderAPI::PrintCallback& callback) {
  std::string extension_id;
  std::string internal_printer_id;
  if (!ParsePrinterId(job.printer_id, &extension_id, &internal_printer_id)) {
    callback.Run(false, PrinterProviderAPI::GetDefaultPrintError());
    return;
  }

  EventRouter* event_router = EventRouter::Get(browser_context_);
  if (!event_router->ExtensionHasEventListener(
          extension_id, api::printer_provider::OnPrintRequested::kEventName)) {
    callback.Run(false, PrinterProviderAPI::GetDefaultPrintError());
    return;
  }

  api::printer_provider::PrintJob print_job;
  print_job.printer_id = internal_printer_id;

  JSONStringValueDeserializer deserializer(job.ticket_json);
  scoped_ptr<base::Value> ticket_value(deserializer.Deserialize(NULL, NULL));
  if (!ticket_value ||
      !api::printer_provider::PrintJob::Ticket::Populate(*ticket_value,
                                                         &print_job.ticket)) {
    callback.Run(false, api::printer_provider::ToString(
                            api::printer_provider::PRINT_ERROR_INVALID_TICKET));
    return;
  }

  print_job.content_type = job.content_type;
  print_job.title = base::UTF16ToUTF8(job.job_title);
  int request_id = pending_print_requests_[extension_id].Add(job, callback);

  scoped_ptr<base::ListValue> internal_args(new base::ListValue);
  // Request id is not part of the public API and it will be massaged out in
  // custom bindings.
  internal_args->AppendInteger(request_id);
  internal_args->Append(print_job.ToValue().release());
  scoped_ptr<Event> event(
      new Event(events::PRINTER_PROVIDER_ON_PRINT_REQUESTED,
                api::printer_provider::OnPrintRequested::kEventName,
                internal_args.Pass()));
  event_router->DispatchEventToExtension(extension_id, event.Pass());
}

const PrinterProviderPrintJob* PrinterProviderAPIImpl::GetPrintJob(
    const Extension* extension,
    int request_id) const {
  auto it = pending_print_requests_.find(extension->id());
  if (it == pending_print_requests_.end())
    return nullptr;
  return it->second.GetPrintJob(request_id);
}

void PrinterProviderAPIImpl::DispatchGetUsbPrinterInfoRequested(
    const std::string& extension_id,
    scoped_refptr<UsbDevice> device,
    const PrinterProviderAPI::GetPrinterInfoCallback& callback) {
  EventRouter* event_router = EventRouter::Get(browser_context_);
  if (!event_router->ExtensionHasEventListener(
          extension_id,
          api::printer_provider::OnGetUsbPrinterInfoRequested::kEventName)) {
    callback.Run(base::DictionaryValue());
    return;
  }

  int request_id =
      pending_usb_printer_info_requests_[extension_id].Add(callback);
  api::usb::Device api_device;
  UsbGuidMap::Get(browser_context_)->GetApiDevice(device, &api_device);

  scoped_ptr<base::ListValue> internal_args(new base::ListValue());
  // Request id is not part of the public API and it will be massaged out in
  // custom bindings.
  internal_args->AppendInteger(request_id);
  internal_args->Append(api_device.ToValue());
  scoped_ptr<Event> event(
      new Event(events::PRINTER_PROVIDER_ON_GET_USB_PRINTER_INFO_REQUESTED,
                api::printer_provider::OnGetUsbPrinterInfoRequested::kEventName,
                internal_args.Pass()));
  event_router->DispatchEventToExtension(extension_id, event.Pass());
}

void PrinterProviderAPIImpl::OnGetPrintersResult(
    const Extension* extension,
    int request_id,
    const PrinterProviderInternalAPIObserver::PrinterInfoVector& result) {
  base::ListValue printer_list;

  // Update some printer description properties to better identify the extension
  // managing the printer.
  for (size_t i = 0; i < result.size(); ++i) {
    scoped_ptr<base::DictionaryValue> printer(result[i]->ToValue());
    UpdatePrinterWithExtensionInfo(printer.get(), extension);
    printer_list.Append(printer.Pass());
  }

  pending_get_printers_requests_.CompleteForExtension(extension->id(),
                                                      request_id, printer_list);
}

void PrinterProviderAPIImpl::OnGetCapabilityResult(
    const Extension* extension,
    int request_id,
    const base::DictionaryValue& result) {
  pending_capability_requests_[extension->id()].Complete(request_id, result);
}

void PrinterProviderAPIImpl::OnPrintResult(
    const Extension* extension,
    int request_id,
    api::printer_provider_internal::PrintError error) {
  const std::string error_str =
      error == api::printer_provider_internal::PRINT_ERROR_NONE
          ? PrinterProviderAPI::GetDefaultPrintError()
          : api::printer_provider_internal::ToString(error);
  pending_print_requests_[extension->id()].Complete(
      request_id, error == api::printer_provider_internal::PRINT_ERROR_OK,
      error_str);
}

void PrinterProviderAPIImpl::OnGetUsbPrinterInfoResult(
    const Extension* extension,
    int request_id,
    const api::printer_provider::PrinterInfo* result) {
  if (result) {
    scoped_ptr<base::DictionaryValue> printer(result->ToValue());
    UpdatePrinterWithExtensionInfo(printer.get(), extension);
    pending_usb_printer_info_requests_[extension->id()].Complete(request_id,
                                                                 *printer);
  } else {
    pending_usb_printer_info_requests_[extension->id()].Complete(
        request_id, base::DictionaryValue());
  }
}

void PrinterProviderAPIImpl::OnExtensionUnloaded(
    content::BrowserContext* browser_context,
    const Extension* extension,
    UnloadedExtensionInfo::Reason reason) {
  pending_get_printers_requests_.FailAllForExtension(extension->id());

  auto print_it = pending_print_requests_.find(extension->id());
  if (print_it != pending_print_requests_.end()) {
    print_it->second.FailAll();
    pending_print_requests_.erase(print_it);
  }

  auto capability_it = pending_capability_requests_.find(extension->id());
  if (capability_it != pending_capability_requests_.end()) {
    capability_it->second.FailAll();
    pending_capability_requests_.erase(capability_it);
  }

  auto usb_it = pending_usb_printer_info_requests_.find(extension->id());
  if (usb_it != pending_usb_printer_info_requests_.end()) {
    usb_it->second.FailAll();
    pending_usb_printer_info_requests_.erase(usb_it);
  }
}

bool PrinterProviderAPIImpl::WillRequestPrinters(
    int request_id,
    content::BrowserContext* browser_context,
    const Extension* extension,
    Event* event,
    const base::DictionaryValue* listener_filter) {
  if (!extension)
    return false;
  EventRouter* event_router = EventRouter::Get(browser_context_);
  if (!event_router->ExtensionHasEventListener(
          extension->id(),
          api::printer_provider::OnGetPrintersRequested::kEventName)) {
    return false;
  }

  return pending_get_printers_requests_.AddSource(request_id, extension->id());
}

}  // namespace

// static
PrinterProviderAPI* PrinterProviderAPI::Create(
    content::BrowserContext* context) {
  return new PrinterProviderAPIImpl(context);
}

// static
std::string PrinterProviderAPI::GetDefaultPrintError() {
  return api::printer_provider_internal::ToString(
      api::printer_provider_internal::PRINT_ERROR_FAILED);
}

}  // namespace extensions