Reset PIXEL_UNPACK_BUFFER at texture manager initialization time

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index 9d202812418477abb98d43c781d33ce2a649b792..309f58aa001d3a5d1cc268eb44d08d6f3ad25335 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -3002,6 +3002,14 @@ bool GLES2DecoderImpl::Initialize(
     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.