Add a manifest property declaring USB printers supported by an app.

extensions/common/api/printer_provider/usb_printer_manifest_handler.cc

Index: extensions/common/api/printer_provider/usb_printer_manifest_handler.cc
diff --git a/extensions/common/api/printer_provider/usb_printer_manifest_handler.cc b/extensions/common/api/printer_provider/usb_printer_manifest_handler.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e356050b7e116491badda09cbf2b7022029ed061
--- /dev/null
+++ b/extensions/common/api/printer_provider/usb_printer_manifest_handler.cc
@@ -0,0 +1,37 @@
+// 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/common/api/printer_provider/usb_printer_manifest_handler.h"
+
+#include "extensions/common/api/printer_provider/usb_printer_manifest_data.h"
+#include "extensions/common/extension.h"
+#include "extensions/common/manifest_constants.h"
+
+namespace extensions {
+
+UsbPrinterManifestHandler::UsbPrinterManifestHandler() {
+}
+
+UsbPrinterManifestHandler::~UsbPrinterManifestHandler() {
+}
+
+bool UsbPrinterManifestHandler::Parse(Extension* extension,
+                                      base::string16* error) {
+  const base::Value* usb_printers = nullptr;
+  CHECK(extension->manifest()->Get(manifest_keys::kUsbPrinters, &usb_printers));
+  scoped_ptr<UsbPrinterManifestData> data =
+      UsbPrinterManifestData::FromValue(*usb_printers, error);
+  if (!data) {
+    return false;
+  }
+
+  extension->SetManifestData(manifest_keys::kUsbPrinters, data.release());
+  return true;
+}
+
+const std::vector<std::string> UsbPrinterManifestHandler::Keys() const {
+  return SingleKey(manifest_keys::kUsbPrinters);
+}
+
+}  // namespace extensions