Use a singleton 1x1 offscreen surface for all TextureImageTransportSurface instances.

content/common/gpu/gpu_channel_manager.cc

Index: content/common/gpu/gpu_channel_manager.cc
diff --git a/content/common/gpu/gpu_channel_manager.cc b/content/common/gpu/gpu_channel_manager.cc
index be60a19413468e7bca9090760b360de78b511651..4774476f6d4539f45d4d61196ee8bc155fbcec47 100644
--- a/content/common/gpu/gpu_channel_manager.cc
+++ b/content/common/gpu/gpu_channel_manager.cc
@@ -175,3 +175,25 @@ void GpuChannelManager::LoseAllContexts() {
 void GpuChannelManager::OnLoseAllContexts() {
   gpu_channels_.clear();
 }
+
+gfx::GLSurface* GpuChannelManager::AllocMakeCurrentSurface() {
+  if (make_current_surface_.get()) {
+    make_current_surface_->AddRef();
+  } else {
+    make_current_surface_ = gfx::GLSurface::CreateOffscreenGLSurface(
+        false, gfx::Size(1, 1));
+  }
+  return make_current_surface_.get();
+}
+
+void GpuChannelManager::ReleaseMakeCurrentSurface() {
+  if (make_current_surface_.get()) {
+    if (make_current_surface_->HasOneRef()) {

[piman, 2012/09/25 00:12:18]

This is bogus, because you don't have a way to know if the last person to call
this has released its last reference (think posted tasks).

I don't think there's any good reason not to hold on to the surface once it's
been created, until the GpuChannelManager gets destroyed.

So I would do instead:
gfx::GLSurface* GpuChannelManager::GetDefaultOffscreenSurface() {
  if (!default_offscreen_surface_.get()) {
    default_offscreen_surface_ = gfx::GLSurface::CreateOffscreenGLSurface(false,
gfx::Size(1, 1));
  }
  return default_offscreen_surface_.get();
}

And Destroy() in the destructor, after releasing the channels.

[hshi1, 2012/09/25 00:26:34]

Done.

+      make_current_surface_->Destroy();
+      make_current_surface_ = NULL;
+    } else {
+      make_current_surface_->Release();
+    }
+  }
+}
+