[Android] Sanitize APK signing file timestamps.

build/android/gyp/finalize_apk.py

Index: build/android/gyp/finalize_apk.py
diff --git a/build/android/gyp/finalize_apk.py b/build/android/gyp/finalize_apk.py
index d71cb8fc7e7704fa58c20bebb2af6e83789d59bd..bf389320397416f7e3e192e87c22773ea4dedd09 100755
--- a/build/android/gyp/finalize_apk.py
+++ b/build/android/gyp/finalize_apk.py
@@ -11,6 +11,7 @@ import optparse
 import shutil
 import sys
 import tempfile
+import zipfile
 
 from util import build_utils
 
@@ -143,6 +144,15 @@ def FinalizeApk(options):
     JarSigner(options.key_path, options.key_name, options.key_passwd,
               apk_to_sign, signed_apk_path)
 
+    # Make the signing files hermetic.
+    with tempfile.NamedTemporaryFile(suffix='.zip') as hermetic_signed_apk:
+      with zipfile.ZipFile(signed_apk_path, 'r') as zi:
+        with zipfile.ZipFile(hermetic_signed_apk, 'w') as zo:
+          for info in zi.infolist():
+            info.date_time = build_utils.HERMETIC_TIMESTAMP
+            zo.writestr(info, zi.read(info.filename))
+      shutil.copy(hermetic_signed_apk.name, signed_apk_path)
+
     if options.load_library_from_zip:
       # Reorder the contents of the APK. This re-establishes the canonical
       # order which means the library will be back at its page aligned location.