gpu: Disallow zero sized offscreen framebuffers

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 2446 matching lines @@
 bool GLES2DecoderImpl::Initialize(
     const scoped_refptr<gfx::GLSurface>& surface,
     const scoped_refptr<gfx::GLContext>& context,
     bool offscreen,
     const gfx::Size& offscreen_size,
     const DisallowedFeatures& disallowed_features,
     const std::vector<int32>& attribs) {
   TRACE_EVENT0("gpu", "GLES2DecoderImpl::Initialize");
   DCHECK(context->IsCurrent(surface.get()));
   DCHECK(!context_.get());
+  DCHECK(!offscreen || !offscreen_size.IsEmpty());

[hendrikw, 2015/04/24 18:33:39]

In my first change, I also DCHECK'd that glGetError() == GL_NO_ERROR near the
end of the function, but we have some mocks that didn't agree with that.

I think it makes sense to catch this, but maybe I should be calling
LOCAL_COPY_REAL_GL_ERRORS_TO_WRAPPER, then DCHECK on the result of
LOCAL_PEEK_GL_ERROR? 

I suspect that LOCAL_COPY_REAL_GL_ERRORS_TO_WRAPPER will cause the same mock
functions to still fail, but that could probably be fixed, I think I need to
override GetError somewhere.

If an error were to happen, we probably want it copied into the state, right? 
Maybe we want to even fail the initialize when an error occurs (we'd probably
want to check the error going into the function too then).

What do you think?

 
   ContextCreationAttribHelper attrib_parser;
   if (!attrib_parser.Parse(attribs))
     return false;
 
   surfaceless_ = surface->IsSurfaceless() && !offscreen;
 
   set_initialized();
   gpu_state_tracer_ = GPUStateTracer::Create(&state_);
 
@@ skipping 10144 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