Update application_service.cc

I suppose this place should be 'false' because actually the Installation is 'failed' due to 'it's already installed', isn't it?
[Runtime] Add Manifest keys handler mechanism

The key handler can parse specific member in manifest.json for more
information, and save these information into the Application object, by
this, it will be easier to use without parsing these information every
time. The mechanism also can treat dependence relationship between
Manifest keys, it make sure that a high priority key will be always
parsed before a low one, means that when parsing the low priority key,
all required information has been prepared yet.

The key handler also can validate if the key value is allowed for this
application.
[SysApps] Add the convenience classes and prototypes

These C++ classes and JavaScript prototypes are helpers for the common
places that appear all around the SysApps APIs specifications.

The main features are:

- Helpers for creating objects managed by the extension.
- Easy way of declaring API methods.
- EventTarget implementation, and thus, helpers for dealing with
  events.

For more information, check the documentation on the code.
[SysApps] Add unit tests for the convinience classes
[SysApps] Add browser tests for the common JavaScript API

These tests are testing the functionality of the helper JavaScript
prototypes and objects, like the EventTarget.
[Extensions] Check for conflicting entry points in the ModuleSystem

As we may have extensions coming from various processes, think that internal
extensions are run in the Browser Process and external extensions are run in
the Extension Process, the only point when we have all information of all the
extensions that would be run for a context is the module system.

So, if conflicting entry points are found, we log this as an warning and do
not register the extension.
[Runtime Model] Implement non-persistent main document.

The following CL is to implement
https://crosswalk-project.org/jira/browse/XWALK-2.

The CL makes ApplicationProcessManager as an Observer for Runtime
objects. Therefore, whenever a Runtime object/Window is added or
removed, the ApplicationProcessManager could be notified.
[Runtime] Add application test API and adjust API browser test

An internal extension for application API test is created to explicitly return
the API test result. For example, with this API we don't to need wait and test
the page title or Runtime count anymore, a call to xwalk.app.test.notifyPass()
or xwalk.app.test.notifyFail() will return the test result to runtime process.

The application API browser test will register this extension in setup phase.
And block wait for the test complete.
[Runtime] Add application test API browser test
[Android][Extensions] Modify error message to comply with W3C spec
Merge pull request #1075 from fyraimar/fix_error_msg

[Android][Extensions] Modify error message to comply with W3C spec
Merge pull request #1041 from mbbill/patch-2

The return value indicating 'already installed' should be false.
Merge pull request #956 from seanlong/xiang_api

[Runtime] Add application test API and adjust API browser test
Merge pull request #926 from shaochangbin/non-persistent-main-document

[Runtime] Implement Non-persistent main document
Merge pull request #754 from takethathe/handler

[Runtime] Add Manifest keys handler mechanism
Enable overlay scrollbars for all platforms

We need overlay scrollbars for Tizen and any platform supporting
viewport changes (@viewport or meta tag). Chromium is going in the
same direction.

To get the right size, offset from viewport edge and fade out,
additional changes are needed to Chromium.
Merge pull request #1081 from kenchris/overlaysb

Enable overlay scrollbars for all platforms
[Extensions] Disable the Extension Framework entirely for --install and --uninstall

As mentioned in https://github.com/crosswalk-project/crosswalk/issues/839,
we shouldn't be bootstrapping the entire BrowserProcess workflow when using
xwalk --install or xwalk --uninstall.

This patch disables the ExtensionService creation, the Extensions
loading and the Extensions registering as a workaround for the
crash mentioned in https://crosswalk-project.org/jira/browse/XWALK-31 .
Merge pull request #1040 from vcgomes/module-system-check-entry-points

[Extensions] Check for conflicting entry points in the ModuleSystem
Merge pull request #1083 from jeez/fix-segfault-crosswalk

[Extensions] Disable the Extension Framework entirely for --install and --uninstall