Fix up javac.py's depfile to include all relevant inputs

build/android/gyp/javac.py

 #!/usr/bin/env python
 #
 # Copyright 2013 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 distutils.spawn
 import optparse
 import os
 import shutil
@@ skipping 402 matching lines @@
   colorama.init()
 
   argv = build_utils.ExpandFileArgs(argv)
   options, java_files = _ParseOptions(argv)
 
   if options.src_gendirs:
     java_files += build_utils.FindInDirectories(options.src_gendirs, '*.java')
 
   java_files = _FilterJavaFiles(java_files, options.javac_includes)
 
-  javac_cmd = ['javac']
   if options.use_errorprone_path:
-    javac_cmd = [options.use_errorprone_path] + ERRORPRONE_OPTIONS
+    javac_path = options.use_errorprone_path
+    javac_cmd = [javac_path] + ERRORPRONE_OPTIONS
+  else:
+    javac_path = distutils.spawn.find_executable('javac')
+    javac_cmd = [javac_path]
 
   javac_cmd.extend((
       '-g',
       # Chromium only allows UTF8 source files.  Being explicit avoids
       # javac pulling a default encoding from the user's environment.
       '-encoding', 'UTF-8',
       # Make sure we do not pass an empty string to -classpath and -sourcepath.
       '-classpath', ':'.join(options.classpath) or ':',
       # Prevent compiler from compiling .java files not listed as inputs.
       # See: http://blog.ltgt.net/most-build-tools-misuse-javac/
@@ skipping 30 matching lines @@
     if options.classpath[0].endswith('.interface.jar'):
       classpath_inputs.extend(options.classpath)
     else:
       # TODO(agrieve): Remove this .TOC heuristic once GYP is no more.
       for path in options.classpath:
         if os.path.exists(path + '.TOC'):
           classpath_inputs.append(path + '.TOC')
         else:
           classpath_inputs.append(path)
 
-  # Compute the list of paths that when changed, we need to rebuild.
-  input_paths = classpath_inputs + options.java_srcjars + java_files
+  # GN already knows of java_files, so listing them just make things worse when
+  # they change.
+  depfile_deps = [javac_path] + classpath_inputs + options.java_srcjars
+  input_paths = depfile_deps + java_files
 
   output_paths = [
       options.jar_path,
       options.jar_path.replace('.jar', '.excluded.jar'),
   ]
   if options.incremental:
     output_paths.append(options.jar_path + '.pdb')
 
   # An escape hatch to be able to check if incremental compiles are causing
   # problems.
   force = int(os.environ.get('DISABLE_INCREMENTAL_JAVAC', 0))
 
   # List python deps in input_strings rather than input_paths since the contents
   # of them does not change what gets written to the depsfile.
   build_utils.CallAndWriteDepfileIfStale(
       lambda changes: _OnStaleMd5(changes, options, javac_cmd, java_files,
                                   classpath_inputs),
       options,
+      depfile_deps=depfile_deps,
       input_paths=input_paths,
       input_strings=javac_cmd,
       output_paths=output_paths,
       force=force,
       pass_changes=True)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))