[Android] Support embedded mode in packaging tool.

Some developers want to package web app with independent
xwalk's runtime library, and don't care the size of it
too much.

Pacakaging tool would copy all the xwalk's runtime library
into target application package, which includes the
.so, .jar, .apk file etc. By default, packaging tool
uses shared mode for web application.

Sample Usage:
python make_apk.py --name=Intel --package=org.xwalk.example
--app-url=http://www.intel.com --mode=embedded

BUG=https://github.com/crosswalk-project/crosswalk/issues/765
[Android] Disable CORS for file:// schemes.

Cross-Origin request breaks the web security policy, only same-origin
request should be allowed for file:// schemes, so universal access
from file URLs should be closed.

BUG=https://github.com/crosswalk-project/crosswalk/issues/790
Merge pull request #791 from gaochun/permission_control

[Android] Disable Cross-Origin request by default.
Merge pull request #809 from junmin-zhu/embed

[Android] Support embedded mode in packaging tool.
Fix the issue File Download Crash in Debug mode

Crosswalk hits DCHECK_NE(content::DownloadItem::kInvalidId, id) failed, since
chromium upstream improved the code, we needed to override the virtual function
GetNextId().
Please see: https://codereview.chromium.org/15584002
This CL also fixed FileDownload error in Linux trybots.

https://github.com/crosswalk-project/crosswalk/issues/888
Enable Aura build on all platforms except Android

Enable Aura build on all platforms except Android.
Merge pull request #897 from pozdnyakov/Enable_Aura_except_Android

Enable Aura build on all platforms except Android
Remove GTK code from xwalk

Since we're always using aura on linux desktop, GTK-related code in xwalk is deprecated and should be removed.
[Extensions] Test extensions with nested names

Add a test for nested extension names. This models our use case for
Tizen-Extensions-Crosswalk, that have the "tizen" extension as well as
many "tizen.*" subextensions.

The second test is disabled, but will serve to check whether we load a
"leaf" extension on demand.
Merge pull request #890 from cmarcelo/nested-test

[Extensions] Test extensions with nested names
Merge pull request #896 from yinli/FileDownload

Fix the issue File Download Crash in Debug mode
Bump version to 2.31.18.0
Merge pull request #899 from pozdnyakov/Remove_GTK

Remove GTK code from xwalk
Fix the issue that getUserMedia can't work on Linux, Tizen and Windows platform

This is a general fix on Linux, Tizen and Windows platform, since the chromium rebasing
resulted in this issue.
XWalkMediaCaptureDevicesDispatcher::RunRequestMediaAccessPermission wasn't running.
Merge pull request #901 from yinli/getUserMedia_Linux

Fix the issue that getUserMdeida can't work on Linux, Tizen and Windows ...
Add application extension and getManifest(), getMainDocument() API support

The application extension is an internal extension to handle application level
APIs(e.g., runtime events, manifest, package management, etc.).

In this commit two APIs is added, one is xwalk.application.getManifest(see
http://developer.chrome.com/apps/runtime.html#method-getManifest), the other is
xwalk.application.getMainDocument(see
http://developer.chrome.com/apps/runtime.html#method-getBackgroundPage).

We use asynchronous calls for both of these two APIs. getManifest() will
retrieve current running application's manifest dictionary value and post the
value to renderer. getMainDocument() utilizes ApplicationNativeModule to get
RenderView from the main document's routing ID, then return its main frame
global JS object.
Add application browser test base class and application API browser test

ApplicationBrowserTest is a base class for application browser test. Currently
it only provides Runtime status check. It will support other application test
utilities after shared browser process model is supported.

In this commit getManifest() and getMainDocument() API tests are added.