[tracing] Implement composable memory usage estimators.

ui/android/resources/resource_manager.cc

Index: ui/android/resources/resource_manager.cc
diff --git a/ui/android/resources/resource_manager.cc b/ui/android/resources/resource_manager.cc
index 2117572e9040f4ef56fbf92370128479dc5fa530..e6654373c067a7365de2a7175e27549cba37746b 100644
--- a/ui/android/resources/resource_manager.cc
+++ b/ui/android/resources/resource_manager.cc
@@ -4,6 +4,7 @@
 
 #include "ui/android/resources/resource_manager.h"
 
+#include "base/trace_event/estimate_memory_usage.h"
 #include "ui/gfx/geometry/insets_f.h"
 
 namespace ui {
@@ -35,4 +36,9 @@ gfx::Rect ResourceManager::Resource::Border(const gfx::Size& bounds,
                    (size.height() - aperture.height()) * bottom_scale);
 }
 
+size_t ResourceManager::Resource::EstimateMemoryUsage() const {
+  using base::trace_event::EstimateMemoryUsage;
+  return EstimateMemoryUsage(ui_resource);
+}
+
 }  // namespace ui