Allow user to pass in a path for extra dependencies for gpu

gyp/common_variables.gypi

 # Copyright 2012 The Android Open Source Project
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   # Get ready for the ugly...
   #
   # - We have to nest our variables dictionaries multiple levels deep, so that
   #   this and other gyp files can rely on previously-set variable values in
@@ skipping 120 matching lines @@
 
 
       # skia_no_fontconfig - On POSIX systems that would normally use the
       #     SkFontHost_fontconfig interface; use the SkFontHost_linux
       #     version instead.
       'skia_no_fontconfig%': '0',
 
       'skia_sanitizer%': '',
       'skia_scalar%': 'float',
       'skia_mesa%': 0,
+      'skia_gpu_extra_dependency_path%': '',
       'skia_stroke_path_rendering%': 0,
       'skia_android_path_rendering%': 0,
       'skia_resource_cache_mb_limit%': 0,
       'skia_resource_cache_count_limit%': 0,
       'skia_angle%': 0,
       'skia_gdi%': 0,
       'skia_gpu%': 1,
       'skia_osx_deployment_target%': '',
       'skia_profile_enabled%': 0,
       'skia_win_debuggers_path%': '',
@@ skipping 57 matching lines @@
     'mips_dsp%': 0,
     'skia_os%': '<(skia_os)',
     'os_posix%': '<(os_posix)',
 
     'skia_freetype_static%': '<(skia_freetype_static)',
     'skia_giflib_static%': '<(skia_giflib_static)',
     'skia_no_fontconfig%': '<(skia_no_fontconfig)',
     'skia_sanitizer%': '<(skia_sanitizer)',
     'skia_scalar%': '<(skia_scalar)',
     'skia_mesa%': '<(skia_mesa)',
+    'skia_gpu_extra_dependency_path%': '<(skia_gpu_extra_dependency_path)',
     'skia_stroke_path_rendering%': '<(skia_stroke_path_rendering)',
     'skia_android_framework%': '<(skia_android_framework)',
     'skia_use_system_json%': '<(skia_use_system_json)',
     'skia_android_path_rendering%': '<(skia_android_path_rendering)',
     'skia_resource_cache_mb_limit%': '<(skia_resource_cache_mb_limit)',
     'skia_resource_cache_count_limit%': '<(skia_resource_cache_count_limit)',
     'skia_angle%': '<(skia_angle)',
     'skia_poppler_enabled%': '<(skia_poppler_enabled)',
     'skia_arch_width%': '<(skia_arch_width)',
     'skia_arch_type%': '<(skia_arch_type)',
@@ skipping 15 matching lines @@
     'skia_moz2d%': 0,
     'skia_is_bot%': '<!(python -c "import os; print os.environ.get(\'CHROME_HEADLESS\', 0)")',
     'skia_egl%': '<(skia_egl)',
 
     # These are referenced by our .gypi files that list files (e.g. core.gypi)
     #
     'skia_src_path%': '../src',
     'skia_include_path%': '../include',
   },
 }