Revert "Revert 186416"

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 e826abd08186e5908f5f35bda49fdb6cde168cd8..a408db798f28cff0233903702685f5735982165a 100755
--- a/gpu/command_buffer/build_gles2_cmd_buffer.py
+++ b/gpu/command_buffer/build_gles2_cmd_buffer.py
@@ -1176,6 +1176,7 @@ _PEPPER_INTERFACES = [
 #               when they can not be automatically determined.
 # pepper_interface: The pepper interface that is used for this extension
 # invalid_test: False if no invalid test needed.
+# shadowed:     True = the value is shadowed so no glGetXXX call will be made.
 
 _FUNCTION_INFO = {
   'ActiveTexture': {
@@ -1563,7 +1564,13 @@ _FUNCTION_INFO = {
     'decoder_func': 'DoGetBooleanv',
     'gl_test_func': 'glGetBooleanv',
   },
-  'GetBufferParameteriv': {'type': 'GETn', 'result': ['SizedResult<GLint>']},
+  'GetBufferParameteriv': {
+    'type': 'GETn',
+    'result': ['SizedResult<GLint>'],
+    'decoder_func': 'DoGetBufferParameteriv',
+    'expectation': False,
+    'shadowed': True,
+  },
   'GetError': {
     'type': 'Is',
     'decoder_func': 'GetGLError',
@@ -4345,11 +4352,19 @@ class GETnHandler(TypeHandler):
   if (result->size != 0) {
     return error::kInvalidArguments;
   }
-  CopyRealGLErrorsToWrapper();
 """
+    shadowed = func.GetInfo('shadowed')
+    if not shadowed:
+      file.Write("  CopyRealGLErrorsToWrapper();\n");
     file.Write(code)
     func.WriteHandlerImplementation(file)
-    code = """  GLenum error = glGetError();
+    if shadowed:
+      code = """  result->SetNumResults(num_values);
+  return error::kNoError;
+}
+"""
+    else:
+     code = """  GLenum error = glGetError();
   if (error == GL_NO_ERROR) {
     result->SetNumResults(num_values);
   } else {