Add support for GL_CHROMIUM_pixel_transfer_buffer_object.

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 21a92900319b82908184d52b23c46c72ad4f2e74..33690bfbc20fc064b54499afc6375c3dbc8690eb 100755
--- a/gpu/command_buffer/build_gles2_cmd_buffer.py
+++ b/gpu/command_buffer/build_gles2_cmd_buffer.py
@@ -1702,6 +1702,13 @@ _FUNCTION_INFO = {
     'decoder_func': 'DoLinkProgram',
     'impl_func':  False,
   },
+  'MapBufferCHROMIUM': {
+    'gen_cmd': False,
+    'extension': True,
+    'chromium': True,
+    'client_test': False,
+    'chromium': True,
+  },
   'MapBufferSubDataCHROMIUM': {
     'gen_cmd': False,
     'extension': True,
@@ -1924,6 +1931,13 @@ _FUNCTION_INFO = {
     'count': 16,
     'decoder_func': 'DoUniformMatrix4fv',
   },
+  'UnmapBufferCHROMIUM': {
+    'gen_cmd': False,
+    'extension': True,
+    'chromium': True,
+    'client_test': False,
+    'chromium': True,
+  },
   'UnmapBufferSubDataCHROMIUM': {
     'gen_cmd': False,
     'extension': True,