Teach GPU command buffer whether a context is webgl.

gpu/command_buffer/service/gles2_cmd_decoder.h

 // 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.
 
 // This file contains the GLES2Decoder class.
 
 #ifndef GPU_COMMAND_BUFFER_SERVICE_GLES2_CMD_DECODER_H_
 #define GPU_COMMAND_BUFFER_SERVICE_GLES2_CMD_DECODER_H_
 
 #include <vector>
@@ skipping 27 matching lines @@
 class ImageManager;
 class Logger;
 class QueryManager;
 class Texture;
 class VertexArrayManager;
 class ValuebufferManager;
 struct ContextState;
 
 struct DisallowedFeatures {
   DisallowedFeatures()
-      : gpu_memory_manager(false) {
+      : gpu_memory_manager(false),
+        npot_support(false) {

[piman, 2015/06/08 21:40:21]

So, if we add this to the FeatureInfo, that could bring trouble - the
FeatureInfo is shared between all contexts in the same group, but in theory
today one can have a webgl context sharing with a non-webgl context (actually it
used to be that way but we removed it a little while ago).

I think it's a reasonable restriction, but it means we need to validate, when we
create the context, that the context group is compatible, otherwise fail.
Otherwise a NPOT texture would be valid/complete in one context and invalid in
another context and that violates a bunch of assumptions in the TextureManager.

[Zhenyao Mo, 2015/06/08 22:23:22]

I remember we decided each WebGL is in it's own context.  In the future we might
want to share WebGL contexts for shared resources extension purpose.  It seems
that we should not share WebGL and WebGL 2 contexts.

I can add the checks in, but should it be a CHECK/DCHECK or an initialization
failure?

   }
 
   bool gpu_memory_manager;
+  bool npot_support;
 };
 
 typedef base::Callback<void(const std::string& key,
                             const std::string& shader)> ShaderCacheCallback;
 
 // This class implements the AsyncAPIInterface interface, decoding GLES2
 // commands and calling GL.
 class GPU_EXPORT GLES2Decoder : public base::SupportsWeakPtr<GLES2Decoder>,
                                 public CommonDecoder {
  public:
@@ skipping 207 matching lines @@
   bool log_commands_;
   bool unsafe_es3_apis_enabled_;
 
   DISALLOW_COPY_AND_ASSIGN(GLES2Decoder);
 };
 
 }  // namespace gles2
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_SERVICE_GLES2_CMD_DECODER_H_