Implementing FlushMappedBufferRange in 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 c10f19382f03ce1b043d4c3fd18e753af099d4cd..322da0d07963c53101418b4bf702bd3751704df7 100755
--- a/gpu/command_buffer/build_gles2_cmd_buffer.py
+++ b/gpu/command_buffer/build_gles2_cmd_buffer.py
@@ -2889,6 +2889,12 @@ _FUNCTION_INFO = {
     'decoder_func': 'DoFlush',
     'trace_level': 1,
   },
+  'FlushMappedBufferRange': {
+    'decoder_func': 'DoFlushMappedBufferRange',
+    'trace_level': 1,
+    'unit_test': False,
+    'unsafe': True,
+  },
   'FramebufferRenderbuffer': {
     'decoder_func': 'DoFramebufferRenderbuffer',
     'gl_test_func': 'glFramebufferRenderbufferEXT',