Add documentation for MemoryCoordinator-related primitives

content/public/browser/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_PUBLIC_BROWSER_MEMORY_COORDINATOR_H_
 #define CONTENT_PUBLIC_BROWSER_MEMORY_COORDINATOR_H_
 
 #include "base/memory/memory_coordinator_client.h"
 #include "base/process/process_handle.h"
 #include "content/common/content_export.h"
 
 namespace content {
 
 // The interface that represents the browser side of MemoryCoordinator.
 // MemoryCoordinator determines memory state of each process (both browser
 // and renderers) and dispatches state change notifications to its clients.
-// See comments on MemoryCoordinatorClient for details.
+// See comments on MemoryCoordinatorClient for how to use it.

[Ryan Sleevi, 2017/02/25 02:57:10]

I think this comment (line 17) should be deleted entirely.

The MemoryCoordinatorClient doesn't describe how to use the MemoryCoordinator,
it describes how to use the MCC.

For example, a logical question is whether or not I need to explicitly
initialize the MemoryCoordinator (e.g. call MemoryCoorindator::GetInstance()) to
start notifications being processed, whether that's implicit by the
MemoryCoordinatorClient, or something else.

Does that make sense? I'm not sure what's trying to be said here, but I don't
think this comment (past or present) does what it says.

 class CONTENT_EXPORT MemoryCoordinator {
  public:
   virtual ~MemoryCoordinator() {}
 
   static MemoryCoordinator* GetInstance();
 
   // Returns the memory state of the given process handle.
   virtual base::MemoryState GetStateForProcess(base::ProcessHandle handle) = 0;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_MEMORY_COORDINATOR_H_