Revert 232657 "GN: toolchain threading cleanup"

Broke linux clang bots:

../../tools/gn/ninja_helper_unittest.cc:20:9:error: field 'settings' will be initialized after field 'toolchain' [-Werror,-Wreorder]

This happened on your try jobs too.

> GN: toolchain threading cleanup
> 
> Remove the thread-unsafe toolchain pointer on the otherwise-threadsafe Settings object. I replaced it with the toolchain label, and moved the is_default flag from the toolchain to the Settings object.
> 
> This required that I pass the toolchain around in a few more places, but also simplifies some other cases.
> 
> I removed the toolchain prefix from Ninja rules for the default toolchain since that's not necessary any more for GYP compat.
> 
> This fixes an annoying double-free in the toolchain manager. I think my current refactor will clean this up in a later phase.
> 
> R=scottmg@chromium.org
> 
> Review URL: https://codereview.chromium.org/51693002

TBR=brettw@chromium.org

Review URL: https://codereview.chromium.org/46313006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232661 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 232661
Dispatches touch events to captured window

We were doing this before I switched us back to the per window
CaptureClient. We need this since current code assumes SetCapture
captures both mouse and touch events.

This also turned up a bug in CompoundEventFilter. It may end up
showing the cursor on the wrong root, resulting in the cursor
remaining hidden. As we don't need the cursor hiding logic on windows
I'm turning it off for us (windows hides the cursor for us).

TEST=see bug
BUG=311569
R=ananta@chromium.org

Review URL: https://codereview.chromium.org/56053004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232662 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 232662