Reset PIXEL_UNPACK_BUFFER at texture manager initialization 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 <limits.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <stdio.h>
@@ skipping 2984 matching lines @@
 
   // If the failIfMajorPerformanceCaveat context creation attribute was true
   // and we are using a software renderer, fail.
   if (attrib_helper.fail_if_major_perf_caveat &&
       feature_info_->feature_flags().is_swiftshader) {
     group_ = NULL;  // Must not destroy ContextGroup if it is not initialized.
     Destroy(true);
     return false;
   }
 
+  // Reset PIXEL_UNPACK_BUFFER to avoid context creation failure.
+  const char* version_str =
+      reinterpret_cast<const char*>(glGetString(GL_VERSION));
+  std::unique_ptr<gl::GLVersionInfo> version_info;
+  version_info.reset(new gl::GLVersionInfo(version_str, "", ""));
+  if (version_info->IsAtLeastGL(3, 2) || version_info->IsAtLeastGLES(3, 0))

[Zhenyao Mo, 2016/09/08 18:19:23]

This should be feature_info_->IsES3Capable()

[qiankun, 2016/09/09 02:06:44]

IsES3Capable() cannot be used until group_->Initialize() (in line 3013) is done,
because gl_version_info_ is initialized in FeatureInfo::InitializeFeatures().

see below callstack:
#2 0x561847d6e382 gpu::gles2::FeatureInfo::InitializeFeatures()
#3 0x561847d6c1c8 gpu::gles2::FeatureInfo::Initialize()
#4 0x561848dd4e8a gpu::gles2::ContextGroup::Initialize()
#5 0x561848e13dbf gpu::gles2::GLES2DecoderImpl::Initialize()

+    glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);

[Zhenyao Mo, 2016/09/02 17:10:23]

Thanks for tracking down the problem, but this is not the right fix.  The
problem is in virtual context initialization.  We need to fix it at the root
cause instead.

[qiankun, 2016/09/02 23:12:01]

Do you mean moving the code to virtual context initialization? If not, I will
dig it further next week.

+
   if (!group_->Initialize(this, attrib_helper.context_type,
                           disallowed_features)) {
     group_ = NULL;  // Must not destroy ContextGroup if it is not initialized.
     Destroy(true);
     return false;
   }
   CHECK_GL_ERROR();
 
   should_use_native_gmb_for_backbuffer_ =
       attrib_helper.should_use_native_gmb_for_backbuffer;
@@ skipping 14735 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 "base/macros.h"
 #include "gpu/command_buffer/service/gles2_cmd_decoder_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu