[Chrome OS] Move cros deps inside the main chrome repo

Instead of forcing all linux devs to have an acceptable version of git
installed, mitigate the problem of the cros_deps/DEPS file living outside
the main chrome checkout by moving our extra DEPS file inside the main chrome
tree.

Also change our naming convention to be more like that which is in use
elsewhere in the project.

In a week, cros_deps/DEPS will be end-of-lifed.

BUG=None
TEST=None

Review URL: http://codereview.chromium.org/4970003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@66153 0039d316-1c4b-4281-b951-d872f2087c98

tools/cros.DEPS/DEPS

+vars = {
+  "chromium_git": "http://git.chromium.org/git",
+}
+
+deps = {
+  "src/third_party/cros":
+    Var("chromium_git") + "/cros.git@d4465704",
+}