Include USB printers in printer list as "provisional" devices.

chrome/browser/ui/webui/print_preview/extension_printer_handler.cc

Index: chrome/browser/ui/webui/print_preview/extension_printer_handler.cc
diff --git a/chrome/browser/ui/webui/print_preview/extension_printer_handler.cc b/chrome/browser/ui/webui/print_preview/extension_printer_handler.cc
index 3236e3ecda46426e5261994ef313b501b8fbc0f7..d9b6442fd17fce647a0c4282cefa46ab1dcb90a2 100644
--- a/chrome/browser/ui/webui/print_preview/extension_printer_handler.cc
+++ b/chrome/browser/ui/webui/print_preview/extension_printer_handler.cc
@@ -18,12 +18,29 @@
 #include "chrome/browser/local_discovery/pwg_raster_converter.h"
 #include "components/cloud_devices/common/cloud_device_description.h"
 #include "components/cloud_devices/common/printer_description.h"
+#include "device/core/device_client.h"
+#include "device/usb/usb_device.h"
+#include "device/usb/usb_service.h"
+#include "extensions/browser/api/device_permissions_manager.h"
 #include "extensions/browser/api/printer_provider/printer_provider_api.h"
 #include "extensions/browser/api/printer_provider/printer_provider_api_factory.h"
 #include "extensions/browser/api/printer_provider/printer_provider_print_job.h"
+#include "extensions/browser/extension_registry.h"
+#include "extensions/common/api/printer_provider/usb_printer_manifest_data.h"
+#include "extensions/common/permissions/permissions_data.h"
+#include "extensions/common/permissions/usb_device_permission.h"
+#include "extensions/common/permissions/usb_device_permission_data.h"
+#include "extensions/common/value_builder.h"
 #include "printing/pdf_render_settings.h"
 #include "printing/pwg_raster_settings.h"
 
+using device::UsbDevice;
+using extensions::DevicePermissionsManager;
+using extensions::DictionaryBuilder;
+using extensions::Extension;
+using extensions::ExtensionRegistry;
+using extensions::ListBuilder;
+using extensions::UsbPrinterManifestData;
 using local_discovery::PWGRasterConverter;
 
 namespace {
@@ -82,11 +99,37 @@ ExtensionPrinterHandler::~ExtensionPrinterHandler() {
 void ExtensionPrinterHandler::Reset() {
   // TODO(tbarzic): Keep track of pending request ids issued by |this| and
   // cancel them from here.
+  printer_enumeration_complete_ = false;
+  wait_for_usb_enumeration_ = false;
   weak_ptr_factory_.InvalidateWeakPtrs();
 }
 
 void ExtensionPrinterHandler::StartGetPrinters(
     const PrinterHandler::GetPrintersCallback& callback) {
+  // Assume that there can only be one printer enumeration occuring at once.
+  DCHECK(!printer_enumeration_complete_);
+  DCHECK(!wait_for_usb_enumeration_);
+
+  ExtensionRegistry* registry = ExtensionRegistry::Get(browser_context_);
+  for (const auto& extension : registry->enabled_extensions()) {
+    if (UsbPrinterManifestData::Get(extension.get()) &&
+        extension->permissions_data() &&
+        extension->permissions_data()->HasAPIPermission(
+            extensions::APIPermission::kPrinterProvider) &&
+        extension->permissions_data()->HasAPIPermission(
+            extensions::APIPermission::kUsb)) {
+      wait_for_usb_enumeration_ = true;

[tbarzic, 2015/05/28 00:20:00]

break;

[Reilly Grant (use Gerrit), 2015/05/28 21:45:00]

Done.

+    }
+  }
+
+  if (wait_for_usb_enumeration_) {
+    device::UsbService* service = device::DeviceClient::Get()->GetUsbService();
+    DCHECK(service);
+    service->GetDevices(
+        base::Bind(&ExtensionPrinterHandler::OnUsbDevicesEnumerated,
+                   weak_ptr_factory_.GetWeakPtr(), callback));
+  }
+
   extensions::PrinterProviderAPIFactory::GetInstance()
       ->GetForBrowserContext(browser_context_)
       ->DispatchGetPrintersRequested(
@@ -192,6 +235,12 @@ void ExtensionPrinterHandler::WrapGetPrintersCallback(
     const PrinterHandler::GetPrintersCallback& callback,
     const base::ListValue& printers,
     bool done) {
+  if (done) {

[Vitaly Buka (NO REVIEWS), 2015/05/28 16:34:12]

maybe simpler is just to have integer counters:

int enumerations_in_progress_ = 0;
Increment when start
decrement when finish
done if zero

[Reilly Grant (use Gerrit), 2015/05/28 21:45:00]

Done.

+    printer_enumeration_complete_ = true;

[tbarzic, 2015/05/28 00:20:00]

nit: no {}

+  }
+  if (wait_for_usb_enumeration_) {

[tbarzic, 2015/05/28 00:19:59]

remove this and invoke callback as

callback.Run(printers, printer_enumeration_done_ && !wait_for_usb_enumeration_)

[Reilly Grant (use Gerrit), 2015/05/28 21:45:00]

Done.

+    done = false;
+  }
   callback.Run(printers, done);
 }
 
@@ -208,3 +257,58 @@ void ExtensionPrinterHandler::WrapPrintCallback(
     const std::string& status) {
   callback.Run(success, status);
 }
+
+void ExtensionPrinterHandler::OnUsbDevicesEnumerated(
+    const PrinterHandler::GetPrintersCallback& callback,
+    const std::vector<scoped_refptr<UsbDevice>>& devices) {
+  ExtensionRegistry* registry = ExtensionRegistry::Get(browser_context_);
+  DevicePermissionsManager* permissions_manager =
+      DevicePermissionsManager::Get(browser_context_);
+
+  ListBuilder printer_list;
+
+  for (const auto& extension : registry->enabled_extensions()) {
+    const UsbPrinterManifestData* manifest_data =
+        UsbPrinterManifestData::Get(extension.get());
+    const extensions::DevicePermissions* device_permissions =
+        permissions_manager->GetForExtension(extension->id());
+
+    if (!manifest_data || !extension->permissions_data() ||
+        !extension->permissions_data()->HasAPIPermission(
+            extensions::APIPermission::kPrinterProvider) ||

[tbarzic, 2015/05/28 00:20:00]

extract to a separate method (you have the same condition in StartGetPrinters)

[Reilly Grant (use Gerrit), 2015/05/28 21:45:00]

Done.

+        !extension->permissions_data()->HasAPIPermission(
+            extensions::APIPermission::kUsb)) {
+      continue;
+    }
+
+    for (const auto& device : devices) {
+      if (manifest_data->SupportsDevice(device)) {
+        extensions::UsbDevicePermission::CheckParam param(
+            device->vendor_id(), device->product_id(),
+            extensions::UsbDevicePermissionData::UNSPECIFIED_INTERFACE);
+        if (device_permissions->FindUsbDeviceEntry(device) ||
+            extension->permissions_data()->CheckAPIPermissionWithParam(
+                extensions::APIPermission::kUsbDevice, &param)) {
+          // Skip devices the extension already has permission to access.
+          continue;
+        }
+
+        printer_list.Append(
+            DictionaryBuilder()
+                .Set("id", base::StringPrintf("provisional-usb:%s:%u",
+                                              extension->id().c_str(),
+                                              device->unique_id()))
+                .Set("name",
+                     DevicePermissionsManager::GetPermissionMessage(
+                         device->vendor_id(), device->product_id(),
+                         device->manufacturer_string(),
+                         device->product_string(), base::string16(), false))
+                .Set("extensionId", extension->id())
+                .Set("extensionName", extension->name()));

[tbarzic, 2015/05/28 00:20:00]

set a flag "isProvisional" (so it can be distinguished from regular extension
printer)

[Reilly Grant (use Gerrit), 2015/05/28 21:45:00]

Done.

+      }
+    }
+  }
+
+  wait_for_usb_enumeration_ = false;
+  callback.Run(*printer_list.Build().get(), printer_enumeration_complete_);
+}