Support ICU on Android

Support ICU on Android

This CL adds an icu_data application that vends ICU data to clients via shared
memory. We use a sha1hash to validate the integrity of the data. Currently,
this icu_data service is used on Android only. Desktop platforms load the ICU
data table from the file system, as they did before. See the mojo-dev
discussion for more background.

R=jamesr@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/3d359105194acaa98b2b4fa3fbf4801fe677611a

[darin (slow to review), 2015-01-08 00:00:43]

darin@chromium.org changed reviewers:
+ darin@chromium.org

[darin (slow to review), 2015-01-08 00:00:44]

it'd be good to file a bug about the readonly shm support and how it could be
useful here.

[jamesr, 2015-01-08 01:23:08]

https://codereview.chromium.org/826093004/diff/1/mojo/services/icu_data/publi...
File mojo/services/icu_data/public/interfaces/icu_data.mojom (right):

https://codereview.chromium.org/826093004/diff/1/mojo/services/icu_data/publi...
mojo/services/icu_data/public/interfaces/icu_data.mojom:1: // Copyright 2015 The
Chromium Authors. All rights reserved.
could you put this mojom in services/icu_data? we don't currently have users
outside the repo and dumping all our interfaces into mojo/services/.../public
seems like the wrong approach in general

https://codereview.chromium.org/826093004/diff/1/mojo/services/icu_data/publi...
mojo/services/icu_data/public/interfaces/icu_data.mojom:5: module mojo;
icu_data ?

https://codereview.chromium.org/826093004/diff/1/services/icu_data/BUILD.gn
File services/icu_data/BUILD.gn (right):

https://codereview.chromium.org/826093004/diff/1/services/icu_data/BUILD.gn#n...
services/icu_data/BUILD.gn:11: "$root_build_dir/icudtl.dat",
what produces this file? will this change every time we update icu?

https://codereview.chromium.org/826093004/diff/1/services/icu_data/main.cc
File services/icu_data/main.cc (right):

https://codereview.chromium.org/826093004/diff/1/services/icu_data/main.cc#ne...
services/icu_data/main.cc:16: extern "C" const char icu_data_table[];
what does extern "C" ... inside an anonymous namespace mean? these are supposed
to be global?

[abarth-chromium, 2015-01-08 04:09:27]

On 2015/01/08 at 00:00:44, darin wrote:
> it'd be good to file a bug about the readonly shm support and how it could be
useful here.

Will do.

[abarth-chromium, 2015-01-08 04:18:12]

https://codereview.chromium.org/826093004/diff/1/mojo/services/icu_data/publi...
File mojo/services/icu_data/public/interfaces/icu_data.mojom (right):

https://codereview.chromium.org/826093004/diff/1/mojo/services/icu_data/publi...
mojo/services/icu_data/public/interfaces/icu_data.mojom:1: // Copyright 2015 The
Chromium Authors. All rights reserved.
On 2015/01/08 at 01:23:08, jamesr wrote:
> could you put this mojom in services/icu_data? we don't currently have users
outside the repo and dumping all our interfaces into mojo/services/.../public
seems like the wrong approach in general

Sure.  I'm not really clear what the difference is between all these different
folders.

https://codereview.chromium.org/826093004/diff/1/mojo/services/icu_data/publi...
mojo/services/icu_data/public/interfaces/icu_data.mojom:5: module mojo;
On 2015/01/08 at 01:23:08, jamesr wrote:
> icu_data ?

I'm happy to change this.  How do we pick module names?

https://codereview.chromium.org/826093004/diff/1/services/icu_data/BUILD.gn
File services/icu_data/BUILD.gn (right):

https://codereview.chromium.org/826093004/diff/1/services/icu_data/BUILD.gn#n...
services/icu_data/BUILD.gn:11: "$root_build_dir/icudtl.dat",
On 2015/01/08 at 01:23:08, jamesr wrote:
> what produces this file? will this change every time we update icu?

There are several checked into third_party/icu depending on platform.  The
//third_party/icu:icudata target copies it to the output directory.  There's a
README there with some instructions for updating the file that I didn't read
that carefully.

https://codereview.chromium.org/826093004/diff/1/services/icu_data/main.cc
File services/icu_data/main.cc (right):

https://codereview.chromium.org/826093004/diff/1/services/icu_data/main.cc#ne...
services/icu_data/main.cc:16: extern "C" const char icu_data_table[];
On 2015/01/08 at 01:23:08, jamesr wrote:
> what does extern "C" ... inside an anonymous namespace mean? these are
supposed to be global?

I can move the externs outside of the anonymous namespace if you like.  The
names are symbols defined in another translation unit (which happens to be a
plain c translation unit).  If you prefer, I can make the other translation unit
a cc file and move them into the icu_data namespace.

[abarth-chromium, 2015-01-08 18:53:41]

Done.  PTAL

[abarth-chromium, 2015-01-08 18:56:00]

Bug about not having read-only segments is
https://code.google.com/p/chromium/issues/detail?id=447285

[jamesr, 2015-01-08 19:03:11]

lgtm

https://codereview.chromium.org/826093004/diff/20001/services/icu_data/icu_da...
File services/icu_data/icu_data.mojom (right):

https://codereview.chromium.org/826093004/diff/20001/services/icu_data/icu_da...
services/icu_data/icu_data.mojom:5: module icu_data;
re naming conventions I've tried to follow the guidance we have for C++
namespaces:
http://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Namespace_Names
which says roughly to follow directory structure. Most things in //services
(possibly all) use the convention that //services/{foo} is in namespace + module
"foo" since the "services" bit doesn't communicate much information

[abarth-chromium, 2015-01-08 19:08:03]

https://codereview.chromium.org/826093004/diff/20001/services/icu_data/icu_da...
File services/icu_data/icu_data.mojom (right):

https://codereview.chromium.org/826093004/diff/20001/services/icu_data/icu_da...
services/icu_data/icu_data.mojom:5: module icu_data;
On 2015/01/08 at 19:03:11, jamesr wrote:
> re naming conventions I've tried to follow the guidance we have for C++
namespaces:
http://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Namespace_Names
which says roughly to follow directory structure. Most things in //services
(possibly all) use the convention that //services/{foo} is in namespace + module
"foo" since the "services" bit doesn't communicate much information

SGTM.  Thanks!

[abarth-chromium, 2015-01-08 19:25:54]

Committed patchset #2 (id:20001) manually as
3d359105194acaa98b2b4fa3fbf4801fe677611a (presubmit successful).