X11: Use better visuals for OpenGL

gpu/ipc/service/gpu_command_buffer_stub.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/ipc/service/gpu_command_buffer_stub.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 517 matching lines @@
     if (!surface_ || !surface_->Initialize(surface_format)) {
       surface_ = nullptr;
       DLOG(ERROR) << "Failed to create surface.";
       return false;
     }
   }
 
   scoped_refptr<gl::GLContext> context;
   gl::GLShareGroup* gl_share_group = channel_->share_group();
   if (use_virtualized_gl_context_ && gl_share_group) {
-    context = gl_share_group->GetSharedContext();
+    context = gl_share_group->GetSharedContext(surface_.get());
     if (!context.get()) {
-      context = gl::init::CreateGLContext(gl_share_group, default_surface,
+      context = gl::init::CreateGLContext(gl_share_group, surface_.get(),
                                           init_params.attribs.gpu_preference);
       if (!context.get()) {
         DLOG(ERROR) << "Failed to create shared context for virtualization.";
         return false;
       }
       // Ensure that context creation did not lose track of the intended
       // gl_share_group.
       DCHECK(context->share_group() == gl_share_group);
-      gl_share_group->SetSharedContext(context.get());
+      gl_share_group->SetSharedContext(surface_.get(), context.get());

[Julien Isorce Samsung, 2016/09/28 17:42:51]

Just for my understanding, could you explain these changes, I mean not exactly
this line but the overall idea about it and above ? Thx

[Tom (Use chromium acct), 2016/09/28 18:36:01]

Before we were always using the default visual in the GPU process.  Now, we may
be using the default visual and a transparent visual at the same time across
different surfaces, however these are incompatible with each other and cannot be
made current with each other.  So when we get a shared context, we need to pass
a compatible surface now so we know which one to use.

     }
     // This should be either:
     // (1) a non-virtual GL context, or
     // (2) a mock context.
     DCHECK(context->GetHandle() ||
            gl::GetGLImplementation() == gl::kGLImplementationMockGL);
     context = new GLContextVirtual(
         gl_share_group, context.get(), decoder_->AsWeakPtr());
     if (!context->Initialize(surface_.get(),
                              init_params.attribs.gpu_preference)) {
@@ skipping 553 matching lines @@
   Send(new GpuCommandBufferMsg_SwapBuffersCompleted(route_id_, params));
 }
 
 void GpuCommandBufferStub::SendUpdateVSyncParameters(base::TimeTicks timebase,
                                                      base::TimeDelta interval) {
   Send(new GpuCommandBufferMsg_UpdateVSyncParameters(route_id_, timebase,
                                                      interval));
 }
 
 }  // namespace gpu