[GTK] Embed Flash fullscreen widget within browser window, plus HTML5 fullscreen fixes.

This is a continuation of r223715 (http://chromiumcodereview.appspot.com/23477051), to implement the same functionality for the Linux/GTK platform.

1. When using the --embed-flash-fullscreen flag, Flash fullscreen widgets will be embedded within the browser window rather than shown as a separate top-level window.
2. Fixed existing bug where browser fullscreen mode (e.g., for HTML5 video) was completely broken for any window manager that does not respect GTK's fullscreen API (e.g., XMonad).  The solution here is to maintain the browser window's fullscreen state separate from the GTK-reported window state.
3. Relevant clean-ups throughout browser_window_gtk.* and tab_contents_container_gtk.*.

Testing: Same methodology as described in r223715.  Also confirmed that repro steps for bug 286545 now result in correct/expected behavior.  Performed all testing steps with Metacity (a very commonly-used WM) and XMonad (a power-user tiling WM).  Tested Kiosk mode both with and without the --embed-flash-fullscreen flag.

BUG=290403,286545
TEST=See "Testing" above.

Review URL: https://codereview.chromium.org/26754005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228795 0039d316-1c4b-4281-b951-d872f2087c98
app_list: Remove start page transition work around.

NativeViewHostAura::InstallClip is implemented so no need for the work around.

BUG=none.

Review URL: https://codereview.chromium.org/26878007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228796 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228795
Disable custom user32 custom imports on VS2013

The assembler is very broken so it crashes on the stubs file.

We could potentially use yasm or something instead of the MS
assembler if they don't get this fixed by final release.

R=siggi@chromium.org
BUG=288948

Review URL: https://codereview.chromium.org/27072004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228797 0039d316-1c4b-4281-b951-d872f2087c98
base: Add base::TimeTicks::IsHighResNowFastAndReliable

This will allow clients determine if it's okay to call
HighResNow often and rely on its results. If it is not
reliable, the client can use a fallback path that is
better than relying on a bad HighResNow.

BUG=305645

Review URL: https://codereview.chromium.org/27317002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228798 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228797
SVN changes up to revision 228798