Virtual context MakeCurrent tweaks.

content/common/gpu/image_transport_surface_mac.cc

Index: content/common/gpu/image_transport_surface_mac.cc
diff --git a/content/common/gpu/image_transport_surface_mac.cc b/content/common/gpu/image_transport_surface_mac.cc
index c6511046901ff3f949b1168f058c10dd8d717a5f..80378b8d96d0388d3eb81dc3685add9f5889b603 100644
--- a/content/common/gpu/image_transport_surface_mac.cc
+++ b/content/common/gpu/image_transport_surface_mac.cc
@@ -6,6 +6,7 @@
 
 #include "base/mac/scoped_cftyperef.h"
 #include "base/memory/scoped_ptr.h"
+#include "content/common/gpu/gpu_command_buffer_stub.h"
 #include "content/common/gpu/gpu_messages.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gl/gl_bindings.h"
@@ -33,8 +34,10 @@ int RoundUpSurfaceDimension(int number) {
 
 // We are backed by an offscreen surface for the purposes of creating
 // a context, but use FBOs to render to texture backed IOSurface
-class IOSurfaceImageTransportSurface : public gfx::NoOpGLSurfaceCGL,
-                                       public ImageTransportSurface {
+class IOSurfaceImageTransportSurface
+    : public gfx::NoOpGLSurfaceCGL,
+      public ImageTransportSurface,
+      public GpuCommandBufferStub::DestructionObserver {
  public:
   IOSurfaceImageTransportSurface(GpuChannelManager* manager,
                                  GpuCommandBufferStub* stub,
@@ -62,6 +65,9 @@ class IOSurfaceImageTransportSurface : public gfx::NoOpGLSurfaceCGL,
   virtual void OnResize(gfx::Size size, float scale_factor) OVERRIDE;
   virtual void SetLatencyInfo(const ui::LatencyInfo&) OVERRIDE;
 
+  // GpuCommandBufferStub::DestructionObserver implementation.
+  virtual void OnWillDestroyStub() OVERRIDE;
+
  private:
   virtual ~IOSurfaceImageTransportSurface() OVERRIDE;
 
@@ -138,7 +144,6 @@ IOSurfaceImageTransportSurface::IOSurfaceImageTransportSurface(
 }
 
 IOSurfaceImageTransportSurface::~IOSurfaceImageTransportSurface() {
-  Destroy();
 }
 
 bool IOSurfaceImageTransportSurface::Initialize() {
@@ -151,7 +156,12 @@ bool IOSurfaceImageTransportSurface::Initialize() {
 
   if (!helper_->Initialize())
     return false;
-  return NoOpGLSurfaceCGL::Initialize();
+
+  if (!NoOpGLSurfaceCGL::Initialize())

[no sievers, 2013/06/05 00:21:16]

I guess for correctness it should call helper_->Destroy() in the early return
here.

[piman, 2013/06/05 00:33:32]

You're probably right, though it's a NOOP anyway. Not sure why we have it at
all!

[no sievers, 2013/06/05 00:38:04]

Done.

+    return false;
+
+  helper_->stub()->AddDestructionObserver(this);
+  return true;
 }
 
 void IOSurfaceImageTransportSurface::Destroy() {
@@ -313,6 +323,11 @@ void IOSurfaceImageTransportSurface::SetLatencyInfo(
   latency_info_ = latency_info;
 }
 
+void IOSurfaceImageTransportSurface::OnWillDestroyStub() {
+  helper_->stub()->RemoveDestructionObserver(this);
+  Destroy();
+}
+
 void IOSurfaceImageTransportSurface::UnrefIOSurface() {
   // If we have resources to destroy, then make sure that we have a current
   // context which we can use to delete the resources.