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 1441fa3c64de1842c132c9916b81fe8623f2ae0c..b1f7cc3fd95737e540a0e7bb0d448bc5f9e073bc 100755
--- a/gpu/command_buffer/build_gles2_cmd_buffer.py
+++ b/gpu/command_buffer/build_gles2_cmd_buffer.py
@@ -1157,6 +1157,7 @@ _FUNCTION_INFO = {
     'type': 'Bind',
     'decoder_func': 'DoBindBuffer',
     'gen_func': 'GenBuffersARB',
+    'impl_func': False,
   },
   'BindFramebuffer': {
     'type': 'Bind',
@@ -1700,6 +1701,13 @@ _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,
@@ -1922,6 +1930,13 @@ _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,