Use chromeos::Process in libchromeos.a instead of g_spawn_async.

Use chromeos::Process in libchromeos.a instead of g_spawn_async.

Change the order of -l linker flags in SConstruct.chromiumos since libchromeos.a depends on libbase. Without the change, chrome fails to dlopen libcros.so.

BUG=chromium-os:12875
TEST=1) ran 'FEATURES=test emerge-x86-generic libcros' to see the library link order is correct. 2) manually checked the new code could change the layout correctly.

Change-Id: I77ea179f93fac368b76fe596db32d349911993ac

Review URL: http://codereview.chromium.org/6709058
(cherry picked from commit 1167c711c1fd411cc5437c2aab7f64d948be7f6b)

Use g_spawn_async instead of _sync to avoid blocking UI-thread.

This change does the following as well:

* Deprecate getter APIs that are currently unused.
* Stop calling 'setxkbmap -print'. Instead, just remember the last layout and modifier mappings set.

BUG=chromium-os:13029
TEST=1) manually checked 2) ran the unittest

Change-Id: If141b273c5ed455b34ae41c75f9f0e1729163e69

Review URL: http://codereview.chromium.org/6691007
(cherry picked from commit 7688b1249dba6d8ce129e220c2977845666a1aaf)

TBR=satorux

Committed: http://chrome-svn/viewvc/chromeos?view=rev&revision=fcede59