[Tools] Remove support for custom variables in DEPS.xwalk.

We have not needed this for several releases, so get rid of the code to
simplify generate_gclient-xwalk.py a bit.

This is part of the preparations for XWALK-1894.
[Tools] Ignore a smaller subset of directories in a checkout.

The XWALK_SYNC_IGNORE environment variable was never used, and the
upstream wiki page the function
mentions (http://dev.chromium.org/developers/how-tos/get-the-code) does
not contain the "Reducing the size of your checkout" section anymore.

Simplify _AddIgnorepathFromEnv() by just ignoring directories outside
src/ that are never used in a regular Crosswalk checkout.

This is another commit doing some groundwork for XWALK-1894.
[Tools] Stop allowing different DEPS files in generate_gclient-xwalk.py.

This feature has never been used, so let us settle on DEPS.xwalk and
simplify the code a bit.

Also related to XWALK-1894.
[Tools] Remove pylint workaround in generate_gclient-xwalk.py.
[Tools] Move most of the generate_gclient-xwalk's logic to DEPS.xwalk.

Most of the code in generate_gclient-xwalk.py should not exist: it
functioned mostly as a translator that read values from DEPS.xwalk and
changed them into a format suitable for gclient.

We can get rid of this intermediate step by writing DEPS.xwalk in a
gclient-compatible format. In practice, this means that DEPS.xwalk is
now responsible for:

* Setting git revision values for repositories we track, such as
  chromium-crosswalk and ozone-wayland (as before).

* Automatically ignoring some directories in the checkout.

* Setting variables parsed by gclient, such as |solutions|.

All this also allows us to remove a lot of validation code that was
scattered around generate_gclient-xwalk.py.

generate_gclient-xwalk.py now exists merely for compatibility, as it
still needs to parse the XWALK_OS_ANDROID environment variable and the
--cache-dir option and append a few more lines to .gclient-xwalk
accordingly. I can see these features being moved somewhere else and the
script getting removed altogether in the future.

This is a significant step in the preparations for XWALK-1894.
[Android] Display no scaled image when no border specified in LaunchScreen

When no border specified in the manifest, the image should not be scaled, just display
the image centered in the screen.

BUG=XWALK-1998
[Tizen/Desktop] Re-organize storage partition management

This patch removes storage partition cleanup logic from Application
Storage and Package Installer making them completely independent
from browser content API layer. Hence now both of them can be used
outside the browser process (e.g. from 'xwalkctl').

The Application Storage implementation is now much simpler which is
very important as we have plans to create an alternative Application
Storage implementation for Tizen, based on the platform 'app_info.db'.
Merge pull request #2136 from pozdnyakov/storage_partitions

[Tizen/Desktop] Re-organize storage partition management
Merge pull request #2135 from rakuco/preparation-for-xwalk-1894

[Tools] Groundwork for tracking Chromium's dependencies with git.
[Tools] Use .gclient's value of |cache_dir| in .gclient-xwalk.

The previous approach was not easy to use at all, as one had to manually
call `gclient sync' with --nohooks, call generate_gclient-xwalk.py
manually with --cache-dir and then run the other hooks.

Instead, just use the same value as .gclient so that all repositories
are cached in the same location, thus also reducing the differences
between .gclient and .gclient-xwalk.

--cache-dir is still accepted and used if passed for compatibility
reasons; support for it can be removed altogether in the next major
version (Crosswalk 8).

Related to XWALK-1184 and XWALK-1894.
Merge pull request #2139 from rakuco/cache-dir-from-dot-gclient

[Tools] Use .gclient's value of |cache_dir| in .gclient-xwalk.
DEPS.xwalk: Start tracking all Chromium dependencies from git.

Chromium is soon going to switch its canonical source repository to git
and we would have to follow suit anyway. In addition, this makes it
easier to cache directories across machines and, in some cases, the
network communication is faster and more reliable when using git.

Most of the work was already done in previous commits that moved the
majority of the logic in generate_gclient-xwalk.py to DEPS.xwalk itself.

We now simply have to adjust the solutions set in DEPS.xwalk, so that
instead of checking out a Chromium release directory from SVN and
pulling all Chromium dependencies from its DEPS file (which points to
SVN repositories for everything) we point directly to chromium-crosswalk
(which was recently adjusted to contain the commit adjusting DEPS and
.DEPS.git for a certain Chromium release) and its .DEPS.git.

The only unusual part of this commit is the moving of Ozone-Wayland to a
separate gclient solution: we need to do that because it has a .DEPS.git
which overrides gclient's recursion limit and would cause problems
because it too would try fetching Chromium. We explicitly set
|deps_file| in this solution to "" to prevent that.

BUG=XWALK-1894
Merge pull request #2140 from wang16/fix_x86_on_arm

[Android] Prompt dialog when CPU architecture mismatch
Bump version to 8.36.162.0
[Tizen][Runtime] Fix allow-navigation element can not take effect if there are more than 1 in config.xml.

In Tizen core spec, it's said that "if more than 1, the first occurrence MUST be considered (and all others
ignored)." This patch makes the runtime following the spec.

BUG=XWALK-1696
Merge pull request #2133 from kurli/launch_screen_image_fix

[Android] Display no scaled image when no border specified in LaunchScreen
[Tizen] Do not use Crosswalk daemon when installing webapps

The Crosswalk installer shouldn't depend on the Crosswalk service
to be running in order to install applications. This is needed for
example to be able to install applications before the system has
booted.

BUG=XWALK-2028
Merge pull request #2143 from takethathe/fix-duplicate-element

[Tizen][Runtime] Fix allow-navigation element can not take effect if there are more than 1 tags in config.xml
Merge pull request #2141 from rakuco/move-deps.xwalk-to-git

DEPS.xwalk: Start tracking all Chromium dependencies from git.
Merge pull request #2144 from pozdnyakov/app_installation

[Tizen] Do not use Crosswalk daemon when installing webapps