Rename source_prereqs to inputs in the GN build.

chrome/browser/devtools/BUILD.gn

 # Copyright 2014 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.
 
 action("devtools_protocol_constants") {
   script = "//content/public/browser/devtools_protocol_constants_generator.py"
 
   blink_protocol = "//third_party/WebKit/Source/devtools/protocol.json"
-  source_prereqs = [ blink_protocol ]
+  inputs = [ blink_protocol ]
   outputs = [
     "$target_gen_dir/devtools_protocol_constants.cc",
     "$target_gen_dir/devtools_protocol_constants.h",
   ]
 
   args = [ "chrome" ]
   args += rebase_path(outputs, root_build_dir)
   args += [ rebase_path(blink_protocol, root_build_dir) ]
 }
 
@@ skipping 96 matching lines @@
       "devtools_file_system_indexer.cc",
       "devtools_target_impl.cc",
       "devtools_window.cc",
       "devtools_window_base.cc",
       "remote_debugging_server.cc",
     ]
   } else {
     deps += [ "//third_party/libusb" ]
   }
 }