Rename source_prereqs to inputs in the GN build.

content/gpu/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.
 
 import("//content/content.gni")
 
 # We don't support x64 prior to Win7 and D3DCompiler_43.dll is not needed on
 # Vista+.
 need_d3dcompiler = (is_win && cpu_arch == "x86" && directxsdk_exists)
 
@@ skipping 43 matching lines @@
 }
 
 if (need_d3dcompiler) {
   action("extract_d3dcompiler") {
     visibility = ":*"
     script = "//build/extract_from_cab.py"
 
     cabfile = "//third_party/directxsdk/files/Redist/Jun2010_D3DCompiler_43_x86.cab"
     dllfile = "D3DCompiler_43.dll"
 
-    source_prereqs = [ cabfile ]
+    inputs = [ cabfile ]
     outputs = [ "$root_out_dir/$dllfile" ]
 
     args = [
       rebase_path(cabfile, root_build_dir),
       dllfile,
       rebase_path(root_out_dir, root_build_dir),
     ]
   }
 }