Add onGetUsbPrinterInfoRequested event to printerProvider API.

extensions/browser/api/printer_provider/printer_provider_api.h

Index: extensions/browser/api/printer_provider/printer_provider_api.h
diff --git a/extensions/browser/api/printer_provider/printer_provider_api.h b/extensions/browser/api/printer_provider/printer_provider_api.h
index f499e5ecc88dbe0c75ec829c3d74ab2e118d1d91..d4402e50e5e3a4925f12e08de34152783d2ceb05 100644
--- a/extensions/browser/api/printer_provider/printer_provider_api.h
+++ b/extensions/browser/api/printer_provider/printer_provider_api.h
@@ -35,6 +35,8 @@ class PrinterProviderAPI : public KeyedService {
       base::Callback<void(const base::DictionaryValue& capability)>;
   using PrintCallback =
       base::Callback<void(bool success, const std::string& error)>;
+  using UsbAccessGrantedCallback =
+      base::Callback<void(const base::DictionaryValue& printer_info)>;
 
   static PrinterProviderAPI* Create(content::BrowserContext* context);
 
@@ -82,6 +84,12 @@ class PrinterProviderAPI : public KeyedService {
   // It should return NULL if the job for the request does not exist.
   virtual const PrinterProviderPrintJob* GetPrintJob(const Extension* extension,
                                                      int request_id) const = 0;
+
+  // Notifies the given extension that it has been granted access to the given

[tbarzic, 2015/05/27 00:11:03]

Comment is unfinished

[Reilly Grant (use Gerrit), 2015/05/28 21:04:10]

Done.

+  virtual void DispatchGrantUsbPrinterAccess(
+      const std::string& extension_id,
+      int device_id,
+      const PrinterProviderAPI::UsbAccessGrantedCallback& callback) = 0;
 };
 
 }  // namespace extensions