WIP GPU scheduler + delayed activation / tile draw

cc/raster/zero_copy_raster_buffer_provider.cc

Index: cc/raster/zero_copy_raster_buffer_provider.cc
diff --git a/cc/raster/zero_copy_raster_buffer_provider.cc b/cc/raster/zero_copy_raster_buffer_provider.cc
index b0b216201b7cc93dedb31aa0a236ced5e4288253..27134fdf42238550a79224c6dd29087488ce58f7 100644
--- a/cc/raster/zero_copy_raster_buffer_provider.cc
+++ b/cc/raster/zero_copy_raster_buffer_provider.cc
@@ -104,6 +104,18 @@ void ZeroCopyRasterBufferProvider::OrderingBarrier() {
   // No need to sync resources as this provider does not use GL context.
 }
 
+bool ZeroCopyRasterBufferProvider::IsResourceReadyToDraw(
+    const Resource* resource) {
+  return true;
+}
+
+void ZeroCopyRasterBufferProvider::SignalResourcesReadyToDraw(
+    const std::vector<const Resource*>& resources,
+    const base::Closure& callback) {
+  if (!callback.is_null())
+    callback.Run();
+}
+
 ResourceFormat ZeroCopyRasterBufferProvider::GetResourceFormat(
     bool must_support_alpha) const {
   if (resource_provider_->IsResourceFormatSupported(preferred_tile_format_) &&