Have GN take GYP arguments from the command line.

This removes the custom parsing for GYP_DEFINES and takes the parameters via a command-line flag that is formatted like the GN vars flag.

The python GYP wrapper will instead be in charge of doing this (this is a separate patch) and passing properly-formatted args to GN via the command line. This will let us look in all the different flags are taken from in Python and avoid having to write Python dictionary parsing code in C++.

This moves the existing recursive origin setting code to Value so it can be shared, and fixes the "show" command which contained < that confused the Linux shell.

BUG=
R=scottmg@chromium.org

Review URL: https://codereview.chromium.org/89043002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237397 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237397
Do not leak tree nodes on destruction of content::RendererAccessibilityComplete.

Fixes memory leaks in content_browsertests.

BUG=322704
R=dmazzoni@chromium.org

Review URL: https://codereview.chromium.org/88683002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237398 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237398