old_contents: {
    'variables': {
      'use_prebuilt%': 0,
    },  # variables
  
    'includes': [
      'base.gypi',
      'net.gypi',
      'media.gypi',
      'ui.gypi',
      'sql.gypi',
      'jingle.gypi',
    ],
    'targets': [
    ]
  }
  
new_contents: {
    'variables': {
      'use_prebuilt%': 0,
    },  # variables
  
    'target_defaults': {
      'direct_dependent_settings': {
      'include_dirs': [
        'src',
        'include',
      ],
      },
    },
    'includes': [
      'base.gypi',
      'net.gypi',
      'media.gypi',
      'ui.gypi',
      'sql.gypi',
      'jingle.gypi',
    ],
    'targets': [
    ]
  }
  
subject: Add include_dirs into target_defaults of gyp.