Preserve modification timestamp when zipping files.

third_party/zlib/google/zip_reader.h

Index: third_party/zlib/google/zip_reader.h
diff --git a/third_party/zlib/google/zip_reader.h b/third_party/zlib/google/zip_reader.h
index a1f470421525197a68b04bc3bd10a2d8257f467c..0a5322f1a4f22e76123f14db00fca9b36cb4f611 100644
--- a/third_party/zlib/google/zip_reader.h
+++ b/third_party/zlib/google/zip_reader.h
@@ -57,7 +57,8 @@ class ZipReader {
     // Returns 0 if the entry is a directory.
     int64 original_size() const { return original_size_; }
 
-    // Returns the last modified time.
+    // Returns the last modified time. If the time stored in the zip file was
+    // not valid, the unix epoch will be returned.

[satorux1, 2013/12/17 02:32:25]

Please document that the timestamp resolution is two seconds. A reference to the
spec would be nice.

[João Eiras, 2013/12/17 10:15:38]

Done.

     base::Time last_modified() const { return last_modified_; }
 
     // Returns true if the entry is a directory.
@@ -127,7 +128,8 @@ class ZipReader {
   // instead. Returns true on success. OpenCurrentEntryInZip() must be
   // called beforehand.
   //
-  // This function does not preserve the timestamp of the original entry.
+  // This function preserves the timestamp of the original entry. If that
+  // timestamp is not valid, the timestamp will be set to the current time.
   bool ExtractCurrentEntryToFilePath(const base::FilePath& output_file_path);
 
   // Extracts the current entry to the given output directory path using
@@ -138,6 +140,9 @@ class ZipReader {
   //
   // Returns true on success. OpenCurrentEntryInZip() must be called
   // beforehand.
+  //
+  // This function preserves the timestamp of the original entry. If that
+  // timestamp is not valid, the timestamp will be set to the current time.
   bool ExtractCurrentEntryIntoDirectory(
       const base::FilePath& output_directory_path);