Add support for EGL on linux

gyp/gpu.gyp

 # GYP for building gpu
 {
   'target_defaults': {
     'conditions': [
       ['skia_os != "win"', {
         'sources/': [ ['exclude', '_win.(h|cpp)$'],
         ],
       }],
       ['skia_os != "mac"', {
         'sources/': [ ['exclude', '_mac.(h|cpp|m|mm)$'],
         ],
       }],
       ['skia_os != "linux" and skia_os != "chromeos"', {
         'sources/': [ ['exclude', '_unix.(h|cpp)$'],
+                      ['exclude', 'GrGLCreateNativeInterface_egl.cpp'],
         ],
       }],
       ['skia_os != "ios"', {
         'sources/': [ ['exclude', '_iOS.(h|cpp|m|mm)$'],
         ],
       }],
       ['skia_os != "android"', {
         'sources/': [ ['exclude', '_android.(h|cpp)$'],
         ],
       }],
       ['skia_os != "nacl"', {
         'sources/': [ ['exclude', '_nacl.(h|cpp)$'],
         ],
       }],
+      ['skia_os == "nacl" or skia_egl == 0', {
+        'sources/': [ ['exclude', '_egl.(h|cpp)$'],
+        ],
+      }],
+      ['skia_egl == 1', {
+        'sources/': [ ['exclude', '_unix.(h|cpp)$'],
+        ],
+      }],
       # nullify the targets in this gyp file if skia_gpu is 0
       [ 'skia_gpu == 0', {
         'sources/': [
           ['exclude', '.*'],
         ],
         'defines/': [
           ['exclude', '.*'],
         ],
         'include_dirs/': [
            ['exclude', '.*'],
@@ skipping 94 matching lines @@
           ],
           'defines': [
             'GR_CHROME_UTILS=1',
           ],
         }],
         [ 'skia_os == "linux" or skia_os == "chromeos"', {
           'sources!': [
             '../src/gpu/gl/GrGLDefaultInterface_none.cpp',
             '../src/gpu/gl/GrGLCreateNativeInterface_none.cpp',
           ],
+        }],
+        [ '(skia_os == "linux" or skia_os == "chromeos") and skia_egl == 1', {
+          'link_settings': {
+            'libraries': [
+              '-lEGL',
+              '-lGLESv2',
+            ],
+          },
+        }],
+        [ '(skia_os == "linux" or skia_os == "chromeos") and skia_egl == 0', {
           'link_settings': {
             'libraries': [
               '-lGL',
               '-lGLU',
               '-lX11',
             ],
           },
         }],
         [ 'skia_os == "nacl"', {
           'link_settings': {
             'libraries': [
               '-lppapi_gles2',
             ],
           },
         }],
+        [ 'skia_egl==1', {
+          'defines': [
+            'SK_EGL',
+          ],
+        }],
         [ 'skia_mesa and skia_os == "linux"', {
           'link_settings': {
             'libraries': [
               '-lOSMesa',
             ],
           },
         }],
         [ 'skia_os == "mac"', {
           'link_settings': {
             'libraries': [
@@ skipping 51 matching lines @@
             'libraries': [
               '-lGLESv2',
               '-lEGL',
             ],
           },
         }],
       ],
     },
   ],
 }