Add glGetFragDataLocation to gpu command buffer.

gpu/command_buffer/build_gles2_cmd_buffer.py

Index: gpu/command_buffer/build_gles2_cmd_buffer.py
diff --git a/gpu/command_buffer/build_gles2_cmd_buffer.py b/gpu/command_buffer/build_gles2_cmd_buffer.py
index 70dc76d46260444f9139a64ca8ccf60496d8f9f3..5cdad562923e669eaa82d7f10914a3d40b6e4c53 100755
--- a/gpu/command_buffer/build_gles2_cmd_buffer.py
+++ b/gpu/command_buffer/build_gles2_cmd_buffer.py
@@ -2028,7 +2028,16 @@ _FUNCTION_INFO = {
     'cmd_args':
         'GLidProgram program, uint32_t name_bucket_id, GLint* location',
     'result': ['GLint'],
-    'error_return': -1, # http://www.opengl.org/sdk/docs/man/xhtml/glGetAttribLocation.xml
+    'error_return': -1,
+  },
+  'GetFragDataLocation': {
+    'type': 'Custom',
+    'data_transfer_methods': ['shm'],
+    'cmd_args':
+        'GLidProgram program, uint32_t name_bucket_id, GLint* location',
+    'result': ['GLint'],
+    'error_return': -1,
+    'unsafe': True,
   },
   'GetBooleanv': {
     'type': 'GETn',