Revert of ozone: Remove the "drm" software composited platform

build/linux/system.gyp

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'variables': {
     # If any of the linux_link_FOO below are set to 1, then the corresponding
     # target will be linked against the FOO library (either dynamically or
     # statically, depending on the pkg-config files), as opposed to loading the
     # FOO library dynamically with dlopen.
@@ skipping 553 matching lines @@
             'ldflags': [
               '<!@(<(pkg-config) --libs-only-L --libs-only-other xkbcommon)',
             ],
             'libraries': [
               '<!@(<(pkg-config) --libs-only-l xkbcommon)',
             ],
           },
         },
       ],
     }],
-    ['ozone_platform_gbm==1', {
+    ['ozone_platform_drm==1 or ozone_platform_gbm==1', {
       'targets': [
         {
           'target_name': 'libdrm',
           'type': 'none',
           'direct_dependent_settings': {
             'cflags': [
               '<!@(<(pkg-config) --cflags libdrm)',
             ],
           },
           'link_settings': {
@@ skipping 678 matching lines @@
                   },
                 }],
               ],
             }],
           ]
         }],
       ],
     },
   ],
 }