Add ES3 command glUnmapBuffer to GPU command buffer.

BUG=429053
TEST=gpu_unittests
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Review URL: https://codereview.chromium.org/996913002

Cr-Commit-Position: refs/heads/master@{#320194}
diff --git a/gpu/command_buffer/cmd_buffer_functions.txt b/gpu/command_buffer/cmd_buffer_functions.txt
index 153aca43..8d32d99 100644
--- a/gpu/command_buffer/cmd_buffer_functions.txt
+++ b/gpu/command_buffer/cmd_buffer_functions.txt
@@ -247,6 +247,7 @@
 GL_APICALL void*        GL_APIENTRY glMapBufferSubDataCHROMIUM (GLuint target, GLintptrNotNegative offset, GLsizeiptr size, GLenum access);
 GL_APICALL void         GL_APIENTRY glUnmapBufferSubDataCHROMIUM (const void* mem);
 GL_APICALL void*        GL_APIENTRY glMapBufferRange (GLenumBufferTarget target, GLintptrNotNegative offset, GLsizeiptr size, GLbitfieldMapBufferAccess access);
+GL_APICALL GLboolean    GL_APIENTRY glUnmapBuffer (GLenumBufferTarget target);
 GL_APICALL void*        GL_APIENTRY glMapTexSubImage2DCHROMIUM (GLenum target, GLint level, GLint xoffset, GLint yoffset, GLsizei width, GLsizei height, GLenum format, GLenum type, GLenum access);
 GL_APICALL void         GL_APIENTRY glUnmapTexSubImage2DCHROMIUM (const void* mem);
 GL_APICALL void         GL_APIENTRY glResizeCHROMIUM (GLuint width, GLuint height, GLfloat scale_factor);