Add delegate and factory function for ChildMemoryCoordinator

components/memory_coordinator/child/child_memory_coordinator_impl.h

Index: components/memory_coordinator/child/child_memory_coordinator_impl.h
diff --git a/components/memory_coordinator/child/child_memory_coordinator_impl.h b/components/memory_coordinator/child/child_memory_coordinator_impl.h
index f8bc01ddea635818ef384d4ba2d96282f83eba89..6e71d20b3b81aac0792d39d86053cfa6753cb6e4 100644
--- a/components/memory_coordinator/child/child_memory_coordinator_impl.h
+++ b/components/memory_coordinator/child/child_memory_coordinator_impl.h
@@ -8,6 +8,7 @@
 #include "base/compiler_specific.h"
 #include "components/memory_coordinator/common/client_registry.h"
 #include "components/memory_coordinator/common/memory_coordinator_client.h"
+#include "components/memory_coordinator/common/memory_coordinator_export.h"
 #include "components/memory_coordinator/common/memory_coordinator_features.h"
 #include "components/memory_coordinator/public/interfaces/child_memory_coordinator.mojom.h"
 #include "components/memory_coordinator/public/interfaces/memory_coordinator.mojom.h"
@@ -15,6 +16,14 @@
 
 namespace memory_coordinator {
 
+class MEMORY_COORDINATOR_EXPORT ChildMemoryCoordinatorDelegate {
+ public:
+  virtual ~ChildMemoryCoordinatorDelegate() {}
+
+  // Called when the system requests immediate actions to free memory.
+  virtual void OnTrimMemoryImmediately() = 0;
+};
+
 // ChildMemoryCoordinatorImpl is the implementation of ChildMemoryCoordinator.
 // It lives in child processes and is responsible for dispatching memory events
 // to its clients.
@@ -22,21 +31,32 @@ class MEMORY_COORDINATOR_EXPORT ChildMemoryCoordinatorImpl
     : public ClientRegistry,
       NON_EXPORTED_BASE(public mojom::ChildMemoryCoordinator) {
  public:
-  explicit ChildMemoryCoordinatorImpl(mojom::MemoryCoordinatorHandlePtr parent);
+  explicit ChildMemoryCoordinatorImpl(mojom::MemoryCoordinatorHandlePtr parent,
+                                      ChildMemoryCoordinatorDelegate* delegate);
   ~ChildMemoryCoordinatorImpl() override;
 
   // mojom::ChildMemoryCoordinator implementations:
   void OnStateChange(mojom::MemoryState state) override;
 
+ protected:
+  ChildMemoryCoordinatorDelegate* delegate() { return delegate_; }
+
  private:
   friend class ChildMemoryCoordinatorImplTest;
 
   mojo::Binding<mojom::ChildMemoryCoordinator> binding_;
   mojom::MemoryCoordinatorHandlePtr parent_;
+  ChildMemoryCoordinatorDelegate* delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(ChildMemoryCoordinatorImpl);
 };
 
-}  // namespace content
+// Factory function for creating a ChildMemoryCoordinator for the current
+// platform. Doesn't take the ownership of |delegate|.
+MEMORY_COORDINATOR_EXPORT std::unique_ptr<ChildMemoryCoordinatorImpl>
+CreateChildMemoryCoordinator(mojom::MemoryCoordinatorHandlePtr parent,
+                             ChildMemoryCoordinatorDelegate* delegate);
+
+}  // namespace memory_coordinator
 
 #endif  // COMPONENTS_MEMORY_COORDINATOR_CHILD_CHILD_MEMORY_COORDINATOR_IMPL_H_