third_party: Add libdrm.

DEPS

 # This file is used to manage the dependencies of the Chromium src repo. It is
 # used by gclient to determine what version of each dependency to check out, and
 # where.
 #
 # For more information, please refer to the official documentation:
 #   https://sites.google.com/a/chromium.org/dev/developers/how-tos/get-the-code
 #
 # When adding a new dependency, please update the top-level .gitignore file
 # to list the dependency's destination directory.
 #
@@ skipping 407 matching lines @@
       Var('chromium_git') + '/external/liblouis-github.git' + '@' + '5f9c03f2a3478561deb6ae4798175094be8a26c2',
 
     # Used for embedded builds. CrOS & Linux use the system version.
     'src/third_party/fontconfig/src':
       Var('chromium_git') + '/external/fontconfig.git' + '@' + 'f16c3118e25546c1b749f9823c51827a60aeb5c1',
 
     # Graphics buffer allocator for Chrome OS.
     'src/third_party/minigbm/src':
       Var('chromium_git') + '/chromiumos/platform/minigbm.git' + '@' + '3345977b5e9ef13f97e2e858241297fc4bfc7401',
 
+    # Userspace interface to kernel DRM services.
+    'src/third_party/libdrm/src':
+      Var('chromium_git') + '/chromiumos/third_party/libdrm.git' + '@' + '4c4778123b7b11f750577199644f5d6820851dbb',
+
     # Display server protocol for Linux.
     'src/third_party/wayland/src':
       Var('chromium_git') + '/external/anongit.freedesktop.org/git/wayland/wayland.git' + '@' + '6a18a87727c64719c68168568b9ab1e4d7c2d9c1',
 
     # Wayland protocols that add functionality not available in the core protocol.
     'src/third_party/wayland-protocols/src':
       Var('chromium_git') + '/external/anongit.freedesktop.org/git/wayland/wayland-protocols.git' + '@' + '2e541a36deff5f2e16e25e27f7f93d26822eecc2',
 
     # Wireless Display Software. Used on Chrome OS.
     'src/third_party/wds/src':
@@ skipping 654 matching lines @@
 ]
 
 recursedeps = [
   # buildtools provides clang_format, libc++, and libc++abi
   'src/buildtools',
   # android_tools manages the NDK.
   'src/third_party/android_tools',
   # ANGLE manages DEPS that it also owns the build files for, such as dEQP.
   ("src/third_party/angle", "DEPS.chromium"),
 ]