Add CupsFilter extraction from resolved ppds for printing.

chromeos/printing/ppd_provider.h

 // Copyright 2016 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.
 
 #ifndef CHROMEOS_PRINTING_PPD_PROVIDER_H_
 #define CHROMEOS_PRINTING_PPD_PROVIDER_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 39 matching lines @@
 
   // Construction-time options.  Everything in this structure should have
   // a sane default.
   struct Options {
     Options() {}
 
     // Root of the ppd serving hierarchy.
     std::string ppd_server_root = "https://www.gstatic.com/chromeos_printing";
   };
 
-  // Result of a ResolvePpd() call.  If the result code is SUCCESS, then the
-  // string holds the contents of a PPD (that may or may not be gzipped).
-  // Otherwise, the string will be empty.
+  // Result of a ResolvePpd() call.
+  // If the result code is SUCCESS, then:
+  //    string holds the contents of a PPD (that may or may not be gzipped).
+  //    required_filters holds the names of the filters referenced in the ppd.
+  // Otherwise, these fields will be empty.
   using ResolvePpdCallback =
-      base::Callback<void(CallbackResultCode, const std::string&)>;
+      base::Callback<void(CallbackResultCode,
+                          const std::string&,
+                          const std::vector<std::string>& required_filters)>;
 
   // Result of a ResolveManufacturers() call.  If the result code is SUCCESS,
   // then the vector contains a sorted list of manufacturers for which we have
   // at least one printer driver.
   using ResolveManufacturersCallback =
       base::Callback<void(CallbackResultCode, const std::vector<std::string>&)>;
 
   // Result of a ResolvePrinters() call.  If the result code is SUCCESS, then
   // the vector contains a sorted list of all printer models from the given
   // manufacturer for which we have a driver.
@@ skipping 61 matching lines @@
 
  protected:
   friend class base::RefCounted<PpdProvider>;
   virtual ~PpdProvider() {}
 };
 
 }  // namespace printing
 }  // namespace chromeos
 
 #endif  // CHROMEOS_PRINTING_PPD_PROVIDER_H_