Disallow active attrib aliasing at shader program link time.

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 4842 matching lines @@
   if (index >= group_->max_vertex_attribs()) {
     LOCAL_SET_GL_ERROR(
         GL_INVALID_VALUE, "glBindAttribLocation", "index out of range");
     return;
   }
   Program* program = GetProgramInfoNotShader(
       program_id, "glBindAttribLocation");
   if (!program) {
     return;
   }
+  // At this point, the program's shaders may not be translated yet,
+  // therefore, we may not find the hashed attribute name.
+  // glBindAttribLocation call with original name is useless.
+  // So instead, we should simply cache the binding, and then call
+  // Program::ExecuteBindAttribLocationCalls() right before link.
   program->SetAttribLocationBinding(name, static_cast<GLint>(index));
+  // TODO(zmo): Get rid of the following glBindAttribLocation call.

[Zhenyao Mo, 2014/10/11 00:25:41]

I didn't do this in this CL, but simply add a TODO to remind myself.

This is because 1) it's orthogonal to this CL; 2) it involves a bunch of test
changes (mostly test expectations).

   glBindAttribLocation(program->service_id(), index, name);
 }
 
 error::Error GLES2DecoderImpl::HandleBindAttribLocationBucket(
     uint32 immediate_data_size,
     const void* cmd_data) {
   const gles2::cmds::BindAttribLocationBucket& c =
       *static_cast<const gles2::cmds::BindAttribLocationBucket*>(cmd_data);
   GLuint program = static_cast<GLuint>(c.program);
   GLuint index = static_cast<GLuint>(c.index);
@@ skipping 6271 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