exo: Implement notification surface support

components/exo/display.cc

Index: components/exo/display.cc
diff --git a/components/exo/display.cc b/components/exo/display.cc
index 7039936a1db49b11a4de1b0ff40cd987806c3a5f..56829ba78af91f254f6ad00469495531a8976ff0 100644
--- a/components/exo/display.cc
+++ b/components/exo/display.cc
@@ -12,6 +12,8 @@
 #include "base/memory/ptr_util.h"
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
+#include "components/exo/notification_surface.h"
+#include "components/exo/notification_surface_registry.h"
 #include "components/exo/shared_memory.h"
 #include "components/exo/shell_surface.h"
 #include "components/exo/sub_surface.h"
@@ -32,7 +34,8 @@ namespace exo {
 ////////////////////////////////////////////////////////////////////////////////
 // Display, public:
 
-Display::Display() {}
+Display::Display()
+    : notification_surface_registry_(new NotificationSurfaceRegistry) {}
 
 Display::~Display() {}
 
@@ -179,4 +182,24 @@ std::unique_ptr<SubSurface> Display::CreateSubSurface(Surface* surface,
   return base::WrapUnique(new SubSurface(surface, parent));
 }
 
+std::unique_ptr<NotificationSurface> Display::CreateNotificationSurface(
+    Surface* surface,
+    const std::string& notification_id) {
+  TRACE_EVENT2("exo", "Display::CreateNotificationSurface", "surface",
+               surface->AsTracedValue(), "notification_id", notification_id);
+
+  if (surface->HasSurfaceDelegate()) {
+    DLOG(ERROR) << "Surface has already been assigned a role";
+    return nullptr;
+  }
+
+  if (notification_surface_registry_->GetSurface(notification_id) != nullptr) {
+    DLOG(ERROR) << "Invalid notification id, id=" << notification_id;
+    return nullptr;
+  }
+
+  return base::WrapUnique(new NotificationSurface(
+      notification_surface_registry(), surface, notification_id));
+}
+
 }  // namespace exo