Move memory_coordinator_client and its registry to base/memory

base/memory/memory_coordinator_client.h

Index: base/memory/memory_coordinator_client.h
diff --git a/components/memory_coordinator/public/interfaces/child_memory_coordinator.mojom b/base/memory/memory_coordinator_client.h
similarity index 54%
copy from components/memory_coordinator/public/interfaces/child_memory_coordinator.mojom
copy to base/memory/memory_coordinator_client.h
index 0c3e889e589a47360523de644a9e9d618760af01..da7104a8d94395decb299f15e86aa79069ce2e32 100644
--- a/components/memory_coordinator/public/interfaces/child_memory_coordinator.mojom
+++ b/base/memory/memory_coordinator_client.h
@@ -2,12 +2,17 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-module memory_coordinator.mojom;
+#ifndef BASE_MEMORY_MEMORY_COORDINATOR_CLIENT_H_
+#define BASE_MEMORY_MEMORY_COORDINATOR_CLIENT_H_
+
+#include "base/base_export.h"
+
+namespace base {
 
 // MemoryState is an indicator that processes can use to guide their memory
 // allocation policies. For example, a process that receives the suspended
 // state can use that as as signal to drop memory caches.
-enum MemoryState {
+enum class MemoryState {
   // The state is unknown.
   UNKNOWN = -1,
   // No memory constraints.
@@ -18,11 +23,16 @@ enum MemoryState {
   SUSPENDED = 2,
 };
 
-// ChildMemoryCoordinator lives in a child process and receives memory events
-// dispatched by the central memory coordinator which lives in the browser
-// process.
-interface ChildMemoryCoordinator {
-  // Called when the central memory coodinator changes the state for child
-  // processes.
-  OnStateChange(MemoryState state);
+// This is an interface for components which can respond to memory status
+// changes.
+class BASE_EXPORT MemoryCoordinatorClient {
+ public:
+  virtual ~MemoryCoordinatorClient() {}
+
+  // Called when memory state has changed.
+  virtual void OnMemoryStateChange(MemoryState state) = 0;
 };
+
+}  // namespace base
+
+#endif  // BASE_MEMORY_MEMORY_COORDINATOR_CLIENT_H_