Add a shallow command buffer flush that doesn't glFlush

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 a6a10d0aacac80dc357bca62d1527f17b6805686..103431c5b834b6e03db243b7ecd9f8a4b0a46db6 100755
--- a/gpu/command_buffer/build_gles2_cmd_buffer.py
+++ b/gpu/command_buffer/build_gles2_cmd_buffer.py
@@ -781,6 +781,8 @@ _PEPPER_INTERFACES = [
 # This table specifies types and other special data for the commands that
 # will be generated.
 #
+# Must match function names specified in "cmd_buffer_functions.txt".
+#
 # cmd_comment:  A comment added to the cmd format.
 # type:         defines which handler will be used to generate code.
 # decoder_func: defines which function to call in the decoder to execute the
@@ -996,6 +998,13 @@ _FUNCTION_INFO = {
     'impl_func': False,
     'decoder_func': 'DoFlush',
   },
+  'ShallowFlushCHROMIUM': {
+    'impl_func': False,
+    'gen_cmd': False,
+    'extension': True,
+    'chromium': True,
+    'client_test': False,
+  },
   'FramebufferRenderbuffer': {
     'decoder_func': 'DoFramebufferRenderbuffer',
     'gl_test_func': 'glFramebufferRenderbufferEXT',