Move attributes and context type out to ContextProviderCommandBuffer.

content/renderer/renderer_blink_platform_impl.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 "content/renderer/renderer_blink_platform_impl.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/files/file_path.h"
@@ skipping 1044 matching lines @@
   gpu::gles2::ContextCreationAttribHelper attributes;
   attributes.alpha_size = -1;
   attributes.depth_size = 0;
   attributes.stencil_size = 0;
   attributes.samples = 0;
   attributes.sample_buffers = 0;
   attributes.bind_generates_resource = false;
 
   attributes.fail_if_major_perf_caveat =
       web_attributes.failIfMajorPerformanceCaveat;
+  DCHECK_GT(web_attributes.webGLVersion, 0u);
   DCHECK_LE(web_attributes.webGLVersion, 2u);
-  if (web_attributes.webGLVersion == 1)
+  if (web_attributes.webGLVersion == 2)
+    attributes.context_type = gpu::gles2::CONTEXT_TYPE_WEBGL2;
+  else
     attributes.context_type = gpu::gles2::CONTEXT_TYPE_WEBGL1;
-  else if (web_attributes.webGLVersion == 2)
-    attributes.context_type = gpu::gles2::CONTEXT_TYPE_WEBGL2;
 
   bool automatic_flushes = true;
   // Prefer discrete GPU for WebGL.
   gfx::GpuPreference gpu_preference = gfx::PreferDiscreteGpu;
 
   scoped_refptr<ContextProviderCommandBuffer> provider(
       new ContextProviderCommandBuffer(
           base::WrapUnique(new WebGraphicsContext3DCommandBufferImpl(
               gpu::kNullSurfaceHandle, GURL(top_document_web_url),
-              gpu_channel_host.get(), attributes, gpu_preference,
-              automatic_flushes)),
-          gpu::SharedMemoryLimits(), share_context,
-          RENDERER_MAINTHREAD_CONTEXT));
+              gpu_channel_host.get(), gpu_preference, automatic_flushes)),
+          gpu::SharedMemoryLimits(), attributes, share_context,
+          command_buffer_metrics::OFFSCREEN_CONTEXT_FOR_WEBGL));

[danakj, 2016/04/30 01:30:45]

The changes in this file are a bit subtle and change behaviour a bit.

What happened before is that WGC3DCBI would pick a type for itself in its
constructor based on the attributes.context_type. From here that meant:

- If webGLVersion was set, it would use OFFSCREEN_CONTEXT_FOR_WEBGL.
- Otherwise, it would use CONTEXT_TYPE_UNKNOWN.

That's the type that would be reported during initialization failures to UMA.

Then after initialization succeeded, ContextProviderCommandBuffer would
overwrite the type on the WGC3DCBImpl with the type we passed in here which was
RENDERER_MAINTHREAD_CONTEXT.

So any lost context events would be reported as RENDERER_MAINTHREAD_CONTEXT.
This seems like a bug, so I have made it always use OFFSCREEN_CONTEXT_FOR_WEBGL
instead.

Also, the only callers of this methods are:

1) WebGL
2) TestPlugin

WebGL always sets a webGLVersion, so I made TestPlugin set a webGLVersion to 1,
and stopped trying to branch/handle the case where webGLVersion was 0, so we
don't have to support CONTEXT_TYPE_UNKNOWN/RENDERER_MAINTHREAD_CONTEXT in here,
which are both weird.

   if (!provider->BindToCurrentThread()) {
     // Collect Graphicsinfo if there is a context failure or it is failed
     // purposefully in case of layout tests.
     Collect3DContextInformationOnFailure(gl_info, gpu_channel_host.get());
     return nullptr;
   }
   return new WebGraphicsContext3DProviderImpl(std::move(provider));
 }
 
 //------------------------------------------------------------------------------
@@ skipping 211 matching lines @@
 }
 
 //------------------------------------------------------------------------------
 
 blink::WebTrialTokenValidator*
 RendererBlinkPlatformImpl::trialTokenValidator() {
   return &trial_token_validator_;
 }
 
 }  // namespace content