Always write data to new buffer in SimulateAttrib0

gpu/command_buffer/service/gles2_cmd_decoder.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"
 
 #include <stdio.h>
 
 #include <algorithm>
 #include <list>
@@ skipping 4944 matching lines @@
       !SafeMultiply(num_vertices, static_cast<GLuint>(sizeof(Vec4)),
                     &size_needed) ||
       size_needed > 0x7FFFFFFFU) {
     SetGLError(GL_OUT_OF_MEMORY, "glDrawXXX: Simulating attrib 0");
     return false;
   }
 
   CopyRealGLErrorsToWrapper();
   glBindBuffer(GL_ARRAY_BUFFER, attrib_0_buffer_id_);
 
-  if (static_cast<GLsizei>(size_needed) > attrib_0_size_) {
+  bool new_buffer = static_cast<GLsizei>(size_needed) > attrib_0_size_;
+  if (new_buffer) {
     glBufferData(GL_ARRAY_BUFFER, size_needed, NULL, GL_DYNAMIC_DRAW);
     GLenum error = glGetError();
     if (error != GL_NO_ERROR) {
       SetGLError(GL_OUT_OF_MEMORY, "glDrawXXX: Simulating attrib 0");
       return false;
     }
-    attrib_0_buffer_matches_value_ = false;
   }
-  if (attrib_0_used &&
-      (!attrib_0_buffer_matches_value_ ||
-       (info->value().v[0] != attrib_0_value_.v[0] ||
-        info->value().v[1] != attrib_0_value_.v[1] ||
-        info->value().v[2] != attrib_0_value_.v[2] ||
-        info->value().v[3] != attrib_0_value_.v[3]))) {
+  if (new_buffer ||
+      (attrib_0_used &&
+       (!attrib_0_buffer_matches_value_ ||
+        (info->value().v[0] != attrib_0_value_.v[0] ||
+         info->value().v[1] != attrib_0_value_.v[1] ||
+         info->value().v[2] != attrib_0_value_.v[2] ||
+         info->value().v[3] != attrib_0_value_.v[3])))) {
     std::vector<Vec4> temp(num_vertices, info->value());
     glBufferSubData(GL_ARRAY_BUFFER, 0, size_needed, &temp[0].v[0]);
     attrib_0_buffer_matches_value_ = true;
     attrib_0_value_ = info->value();
     attrib_0_size_ = size_needed;
   }
 
   glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, NULL);
 
   if (info->divisor())
@@ skipping 3318 matching lines @@
   }
 }
 
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.
 #include "gpu/command_buffer/service/gles2_cmd_decoder_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu