Make Graphics3D::SwapBuffers take a completion callback

chrome/renderer/webgraphicscontext3d_command_buffer_impl.cc

Index: chrome/renderer/webgraphicscontext3d_command_buffer_impl.cc
diff --git a/chrome/renderer/webgraphicscontext3d_command_buffer_impl.cc b/chrome/renderer/webgraphicscontext3d_command_buffer_impl.cc
index 659c8be37ec6abaf1be0d5e5a95b52fa26d93b06..1be54610cbf89ce6ffa1b5915bfd5aa91d452152 100644
--- a/chrome/renderer/webgraphicscontext3d_command_buffer_impl.cc
+++ b/chrome/renderer/webgraphicscontext3d_command_buffer_impl.cc
@@ -116,6 +116,11 @@ bool WebGraphicsContext3DCommandBufferImpl::initialize(
         renderview->routing_id(),
         kWebGraphicsContext3DPerferredGLExtensions,
         attribs);
+    if (context_) {
+      ggl::SetSwapBuffersCallback(

[apatrick, 2010/12/16 03:36:38]

Is there a danger that the callback will keep the RenderView alive until a
SwapBuffers notification comes in (if ever)? I was expecting the callback to be
set on the offscreen context associated with the plugin instance. I already
added one to schedule a composite when a plugin has rendered a frame. Also, what
if the plugin instance is offscreen? We are liable to not schedule a composite
if it is not visible.

[piman, 2010/12/16 04:27:34]

NewCallback doesn't refcount the RenderView, so I don't think there's an issue
there.
Not scheduling a composite is exactly what we want. The callback is meant for
end-to-end rate control, so that the plugin doesn't keep rendering frames that
will never be displayed. This is the same behavior when accelerated compositing
is off.

So plugin's SwapBuffers() [3D] or Flush() [2D] schedules a redraw [compositing
off] or composite [compositing on]. When that one is sent to the GPU process
[compositing on] or browser process [compositing off], DidInitiatePaint needs to
be called. When it is finished, DidFlushPaint needs to be called. This callback
corresponds to RenderWidget::OnUpdateRectAck.

Note that technically this is needed for the 2D case to work correctly in case
of the accelerated compositing (e.g. a 2D pepper plugin with an animated css
transform on it).

+          context_,
+          NewCallback(renderview, &RenderView::DidFlushPaint));
+    }
   } else {
     bool compositing_enabled = !CommandLine::ForCurrentProcess()->HasSwitch(
         switches::kDisableAcceleratedCompositing);