Add MemoryCoordinatorImpl

content/browser/memory/memory_coordinator.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_MEMORY_MEMORY_COORDINATOR_H_
 #define CONTENT_BROWSER_MEMORY_MEMORY_COORDINATOR_H_
 
 #include "base/memory/memory_coordinator_client_registry.h"
-#include "base/memory/singleton.h"
 #include "base/process/process_handle.h"
 #include "content/common/content_export.h"
 #include "content/common/memory_coordinator.mojom.h"
 #include "mojo/public/cpp/bindings/binding.h"
 
 namespace content {
 
 // NOTE: Memory coordinator is under development and not fully working.
 // TODO(bashi): Add more explanations when we implement memory coordinator V0.
 
 class MemoryCoordinatorHandleImpl;
 
 // MemoryCoordinator is responsible for the whole memory management accross the
 // browser and child proceeses. It dispatches memory events to its clients and
 // child processes based on its best knowledge of the memory usage.
 class CONTENT_EXPORT MemoryCoordinator {
  public:
-  ~MemoryCoordinator();
+  virtual ~MemoryCoordinator();
 
   // Singleton factory/accessor.
   static MemoryCoordinator* GetInstance();
 
   // Creates a handle to the provided child process.
   void CreateHandle(int render_process_id,
                     mojom::MemoryCoordinatorHandleRequest request);
 
   // Returns number of children. Only used for testing.
   size_t NumChildrenForTesting();
@@ skipping 14 matching lines @@
   MemoryCoordinator();
 
   // Adds the given ChildMemoryCoordinator as a child of this coordinator.
   void AddChildForTesting(int dummy_render_process_id,
                           mojom::ChildMemoryCoordinatorPtr child);
 
   // Callback invoked by mojo when the child connection goes down. Exposed
   // for testing.
   void OnConnectionError(int render_process_id);
 
- private:
-  friend struct base::DefaultSingletonTraits<MemoryCoordinator>;
-
-  // Helper function of CreateHandle and AddChildForTesting.
-  void CreateChildInfoMapEntry(
-      int render_process_id,
-      std::unique_ptr<MemoryCoordinatorHandleImpl> handle);
-
   // Stores information about any known child processes.
   struct ChildInfo {
     // This object must be compatible with STL containers.
     ChildInfo();
     ChildInfo(const ChildInfo& rhs);
     ~ChildInfo();
 
     mojom::MemoryState memory_state;
     std::unique_ptr<MemoryCoordinatorHandleImpl> handle;
   };
 
   // A map from process ID (RenderProcessHost::GetID()) to child process info.
   using ChildInfoMap = std::map<int, ChildInfo>;
 
+  ChildInfoMap& children() { return children_; }
+
+  virtual void OnChildAdded() {}
+  virtual void OnChildRemoved() {}

[chrisha, 2016/09/30 02:57:20]

Why are these needed? The Impl should be able to infer that a child has been
added or removed by inspecting the map, and need not react immediately.

+
+private:
+  // Helper function of CreateHandle and AddChildForTesting.
+  void CreateChildInfoMapEntry(
+      int render_process_id,
+      std::unique_ptr<MemoryCoordinatorHandleImpl> handle);
+
   // Tracks child processes. An entry is added when a renderer connects to
   // MemoryCoordinator and removed automatically when an underlying binding is
   // disconnected.
   ChildInfoMap children_;
 
   DISALLOW_COPY_AND_ASSIGN(MemoryCoordinator);
 };
 
+// The implementation of MemoryCoordinatorHandle. See memory_coordinator.mojom
+// for the role of this class.
+class MemoryCoordinatorHandleImpl : public mojom::MemoryCoordinatorHandle {

[chrisha, 2016/09/30 02:57:20]

Why do we need to expose this impl detail?

+ public:
+  MemoryCoordinatorHandleImpl(mojom::MemoryCoordinatorHandleRequest request);
+  ~MemoryCoordinatorHandleImpl() override;
+
+  // mojom::MemoryCoordinatorHandle:
+  void AddChild(mojom::ChildMemoryCoordinatorPtr child) override;
+
+  mojom::ChildMemoryCoordinatorPtr& child() { return child_; }
+  mojo::Binding<mojom::MemoryCoordinatorHandle>& binding() { return binding_; }
+
+ private:
+  mojom::ChildMemoryCoordinatorPtr child_;
+  mojo::Binding<mojom::MemoryCoordinatorHandle> binding_;
+
+  DISALLOW_COPY_AND_ASSIGN(MemoryCoordinatorHandleImpl);
+};
+
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_MEMORY_MEMORY_COORDINATOR_H_