Remove the length field from the index entries in data pack files.

Remove the length field from the index entries in data pack files.

After the last index entry, we put an extra entry (id of 0, offset
pointing to where the next entry would start) so we can compute
the size of the last index entry.

This saves 4 bytes per item in data pack files, which is about 10k per
locale pak file.  When compressed, this saves about 237k.

BUG=76285
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=96415

[tony, 2011-08-10 16:37:42]

The test failure is from not being able to apply the binary diff to sample.pak.

[Evan Martin, 2011-08-10 17:28:56]

(random other review comment I wrote before I talked to you in person)

http://codereview.chromium.org/7604012/diff/1/ui/base/resource/data_pack.cc
File ui/base/resource/data_pack.cc (right):

http://codereview.chromium.org/7604012/diff/1/ui/base/resource/data_pack.cc#n...
ui/base/resource/data_pack.cc:44: COMPILE_ASSERT(sizeof(DataPackEntry) == 6,
size_of_header_must_be_six);
I guess this should be "size_of_ENTRY_must_be_six" (but lowercase)

[tony, 2011-08-10 18:41:48]

New version up with an extra entry so we can identify cases where the file is
truncated.  This also makes the read code simpler.

After this patch lands, I'll update
http://dev.chromium.org/developers/design-documents/linuxresourcesandlocalize...
.

[Evan Martin, 2011-08-10 18:52:49]

LGTM