[Android] Implement the http authentication in xwalk default client.

  The implementation is to provide the http anthentication
funtions to support the authentication requirement of some
web site related to username and password, covering the
following:
1 Import and implement a general class of HttpAuthDatabase
  to support common http authentication database interfaces.
  This class imports the android sqlite database to handle
  the username and password data on demand.
2 In default xwalk client, implement the method of
  setHttpAuthUsernamePassword() by calling the related method
  of HttpAuthenDatabase instance to set the username and password.
3 In default xwalk client, implement the method of
  getHttpAuthUsernamePassword() by calling the related method
  of HttpAuthenDatabase instance to query the username and password.

BUG=#784, #787
[Tizen] add the 'gst-plugins-atomisp-devel' buildrequires to spec.

chromium needs the header and lib files exported from this package to drive the
camera device on Tizen 2.1 hardware platforms.

BUG=#864
[Android] Refine the xwalk_core_test_apk target

This fix is to refine the test target to make it more cleaner to add
HTML testing file as apk asset file. Right now, when adding a new HTML
file for testing, you just need to update the 'sources' list without
adding a new entry item in 'copies' list.
[Extensions] Refactoring XWalkExtensionService::RegisterExtension

Nowadays our XWalkExtensionService is only capable of handling
one RenderProcess. Thus, it only has one in_process XWalkExtensionServer
for handling internal extensions. Soon enough this will considerably
change and we will have to be capable of handling one in_process
XWalkExtensionServer per RenderProcess.

This patch is the first step towards this: internal extensions
will be created directly by the XWalkExtensionService::Delegate
"on-demand" every time a new in_process XWalkExtensionServer
is created for a new RenderProcess and it is time to register
the internal extensions on it.

The entity implementing XWalkExtensionService::Delegate is
XWalkBrowserMainParts. This way we keep the old behavior and design
not polluting XWalkExtensionService.

Necessary adjustments were made to RegisterExtensionsCallback and
browser_tests for the same reason.
Enable multithreaded GPU compositing of web content by default.

Enable multithreaded GPU compositing of web content by default, this also enables pinch gesture support on Tizen.
Merge pull request #933 from pozdnyakov/EnableThreadedCompositing

Enable multithreaded GPU compositing of web content by default.
[Extensions] Remove unused function
[Tizen] Fix Glib assertion due to appcore_context.

This patch get rid of following log:
[ERROR:browser_main_loop.cc(228)] GLib: g_source_destroy: assertion `source != NULL' failed

AppcoreContext::Initialize() fails when we launch xwalk in the shell. e.g. > xwalk
It is because appcore_init() can success only if registered application (e.g.
web applications) is launched.

This patch handles the exception that AppcoreContext::Initialize() fails.
[Extensions][Android] Make CreateExtension call XWalkExtensionService directly

XWalkBrowserMainParts is now a XWalkExtensionService::Delegate, meaning that
XWalkExtensionService will call RegisterInternalExtensionsInServer everytime
a new in_process XWalkExtensionServer is created (for a new RenderProcess).

Therefore, XWalkExtensionService::RegisterExtension() has been removed
and XWalkExtensionAndroid will now need to register its extensions on
XWalkBrowserMainParts so them can get correctly registered on-demand
by XWalkExtensionService.
Merge pull request #934 from cmarcelo/remove-dead-code

[Extensions] Remove unused function
[Extensions] Use a vector instead of a map for extension modules

In XWalkModuleSystem, use a vector instead of a map for extension
modules. The number of modules is small and we'll benefit from being
able to easily get sorted iteration later to identify the extension
modules that can be loaded on demand.
Fix build for Windows.

Windows switched to Aura therefore we need to remove the old code
path and use the generic method to access the title. The compilation
failure was due to the fact that NativeWindow type is not anymore
a HWND.

BUG=936
Merge pull request #910 from jeez/refactor-register-extension

[Extensions] Refactoring XWalkExtensionService::RegisterExtension
Merge pull request #937 from cmarcelo/extension-modules-vector

[Extensions] Use a vector instead of a map for extension modules
Bump version to 2.31.21.0
Merge pull request #931 from hmin/refine-test-target

[Android] Refine the xwalk_core_test_apk target
[Android] Remove the wrong dependence in runtime client test apk.

This patch will resolve the issue about wrong dependence in the runtime
client test apk.
In file CrossPackageWrapper.java, the constructor function "CrossPackageWrapper()"
has the judgement about the class loaded. In shared mode, the core shell is not
needed for the runtime client test shell.

BUG=#916
Merge pull request #917 from wuhengzhi/shared_issue

[Android] Remove the wrong dependence in runtime client test apk.
[Android] Create the XWalkRenderViewExt object.

XWalkRenderViewExt is a class that handles several IPCs from the class
XWalkRenderViewHostExt. To make it work, an object of XWalkRenderViewExt
must be created first.
[Android] Fix #705 to support multiple frames for extension mechanism

When there are multiple frames in one page, extension instance will
be created for each frame. But as internal WebFrame is not exposed
in Java side, there is no way for Java side to identify which
instance to send message. This patch exposed instanceID up to Java
side when it receives message which can be used to identify the
target instance when post message to JavaScript side. What's more
a new interface "broadcastMessage" was added to meet the requirement
that Java side may need to broadcast message to all exiting instances.

Changed interfaces for Java extension:
1. postMessage(String msg) -> postMessage(int instanceID, String msg)
2. onMessage(String msg)   -> onMessage(int instanceID, String msg)
3. onSyncMessage(String msg) -> onSyncMessage(int instanceID, String msg)
4. new added: broadcastMessage(String msg)

BUG=#705