[Mac] Fix for build

Use <sys/prctl.h> and prctl() only on Linux (OS_LINUX) and not Posix (OS_POSIX).

This seems to be the way Chromium guards the items.
Add generated main document URL request job support

A generated main document is an empty HTML document which <body> tag contains
JavaScript files specified in manifest.json. Ref to:
http://anssiko.github.io/runtime/app-lifecycle.html#a-single-entry-point-to-the-application

The GeneratedMainDocumentJob implementation is borrowed from Chromium extension
GeneratedBackgroundPageJob. When a URL request matches
"_generated_main_document.html" file name the job will be created and returns
the generated content.
Add main document launch support

Main document is an invisble document no matter whether it is a real file or a
generated one. Working as the main entry of an application, the main document
must be loaded before other pages.(see
http://anssiko.github.io/runtime/app-lifecycle.html)

So the Runtime::Create() is modified to create a Runtime instance without attach
to any app window, and the WebContents' initial size is also set to (0,0).
Runtime::CreateWithDefaultWindow() now works like previous Runtime::Create().
Currently we support application both run from main document and local path,
however the local path support may be deprecated in the future.
Add main document browser test
Merge pull request #656 from seanlong/master

[Runtime] Add main document(aka "event page") launch support
[Tools] Add bump-canary-version.sh.

This script is used to automatically bump Crosswalk's build version (ie. the
"3" in version "1.2.3.4"), so that the automated Canary generation machinery
can used it to bump versions and commit when all canaries build and pass all
tests.

Using a simple, POSIX shell script with Perl one-liners is much quicker than
writing a full-fledged Python script just to perform some glorified sed's,
and I hope the Perl is easy enough to understand.
Merge pull request #697 from rakuco/bump-version-script

[Tools] Add bump-canary-version.sh.
[Tools] Simplify the newline logic in generate_gclient-xwalk.py.
[Tools] Accept --cache-dir in generate_gclient-xwalk.py.

See r210024 in Chromium: the (still experimental) "cache_dir" option in a
.gclient file allows gclient to set up a local mirror for git repositories
(by passing --mirror to `git clone') and then use them to speed up clones by
passing --reference and --shared to `git clone'.

This means that once a repository such as blink-crosswalk is mirrored like
this, creating one or more clones takes a few seconds instead of an hour or
more (provided "cache_dir" is properly specified in the .gclient files).

This feature is not very useful in the general case, as developers do not
normally have multiple clones around or need to clone from scratch very
often, but it helps a great deal in automation, as one can cache the
repositories once and test full builds much faster.

Important note: "cache_dir" is not supported by the depot_tools version
checked out by our Chromium 29.0.1547.57, but most people have their own
copy of depot_tools somewhere else anyway.
Merge pull request #698 from rakuco/gclient-cache-dir

[Tools] Add --cache-dir support to generate_gclient-xwalk.py.
Fix change that went in by mistake

I'm testing things locally without those flags because they are broken
in my test environment. The problem was reported to Kenneth. Sorry for
the noise.
Merge pull request #700 from cmarcelo/fix-wrong-change

Fix change that went in by mistake
Merge pull request #693 from poussa/mac-compile-5

[Mac] Fix build
[Android] Add the file of XWalkDefaultClient.java to Runtime Core.

1  Add the Ssl alert title to the file of android_xwalk_strings.grd.
2  Create a new class XWalkDefaultClient extended from class XWalkClient.
3  Initialize the resources in the constructor function of the class of
   XWalkDefaultClient.
4  Create the method of onReceivedError() to handle the process of
   receiving error.
5  Create the method of onReceivedSslError() to handle the process of
   receiving ssl error.