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

build/android/gyp/javac.py

Index: build/android/gyp/javac.py
diff --git a/build/android/gyp/javac.py b/build/android/gyp/javac.py
index df5325f7f058d5c7915fef1acdc7ed057d855f26..8ab8ea0126ca8417f7d9d3c287bc38373e0ff1aa 100755
--- a/build/android/gyp/javac.py
+++ b/build/android/gyp/javac.py
@@ -94,9 +94,7 @@ def _ExtractClassFiles(jar_path, dest_dir, java_files):
 
 
 def _ConvertToJMakeArgs(javac_cmd, pdb_path):
-  new_args = ['bin/jmake', '-pdb', pdb_path]
-  if javac_cmd[0] != 'javac':
-    new_args.extend(('-jcexec', new_args[0]))
+  new_args = ['bin/jmake', '-pdb', pdb_path, '-jcexec', javac_cmd[0]]
   if md5_check.PRINT_EXPLANATIONS:
     new_args.append('-Xtiming')
 
@@ -420,9 +418,12 @@ def main(argv):
 
   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',
@@ -473,8 +474,10 @@ def main(argv):
         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,
@@ -493,6 +496,7 @@ def main(argv):
       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,