Sort Java AIDL input filenames for makefile stability.

Sort the list of input java files for the aidl build step so that
the contents of generated makefiles in WebView have a stable ordering.

BUG=

Review URL: https://codereview.chromium.org/323803003

Cr-Commit-Position: refs/heads/master@{#292686}

build/java_aidl.gypi

@@ -49,7 +49,7 @@
     ['aidl_import_include != ""', {
       'variables': {
         'additional_aidl_arguments': [ '-I<(aidl_import_include)' ],
-        'additional_aidl_input_paths': [ '<!@(find <(aidl_import_include) -name "*.java")', ]
+        'additional_aidl_input_paths': [ '<!@(find <(aidl_import_include) -name "*.java" | sort)' ],
       }
     }],
   ],