Reland: Add MemoryCoordinator

content/renderer/render_thread_impl.h

Index: content/renderer/render_thread_impl.h
diff --git a/content/renderer/render_thread_impl.h b/content/renderer/render_thread_impl.h
index 9a3795f2ddc0d1d801081766f2b817cad35cf6f6..b7ad13af3307205195f2e6922f24139a573a6230 100644
--- a/content/renderer/render_thread_impl.h
+++ b/content/renderer/render_thread_impl.h
@@ -79,6 +79,10 @@ class AudioHardwareConfig;
 class GpuVideoAcceleratorFactories;
 }
 
+namespace memory_coordinator {
+class ChildMemoryCoordinatorImpl;
+}
+
 namespace scheduler {
 class WebThreadBase;
 }
@@ -643,6 +647,8 @@ class CONTENT_EXPORT RenderThreadImpl
   std::unique_ptr<base::MemoryPressureListener> memory_pressure_listener_;
 
   std::unique_ptr<MemoryObserver> memory_observer_;
+  std::unique_ptr<memory_coordinator::ChildMemoryCoordinatorImpl>
+      memory_coordinator_;
 
   scoped_refptr<base::SingleThreadTaskRunner>
       main_thread_compositor_task_runner_;