memory-infra: Introduce mojo interfaces and service stubs

services/memory_infra/public/interfaces/memory_infra.mojom

+// Copyright 2017 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.
+
+module memory_infra.mojom;
+
+enum DumpType {
+  PERIODIC_INTERVAL,
+  EXPLICITLY_TRIGGERED,
+  PEAK_MEMORY_USAGE,
+  LAST = PEAK_MEMORY_USAGE
+};
+
+enum LevelOfDetail {
+  FIRST,
+  BACKGROUND = FIRST,
+  LIGHT,
+  DETAILED,
+  LAST = DETAILED
+};
+
+struct RequestArgs {
+  uint64 dump_guid;
+  DumpType dump_type;
+  LevelOfDetail level_of_detail;
+};
+
+// Memory Infra clients implement this interface. There should be at most one
+// client per process. 
+interface Client {
+  RequestLocalMemoryDump(RequestArgs args) => (uint64 dump_guid, bool success);

[ssid, 2017/01/11 00:13:25]

I'd prefer Process over Local here since the name of the interface (Client) does
not directly suggest it's per process.
So, Local could mean a Thread also. But, leave it to Primiano for the decision
on naming.

[chiniforooshan1, 2017/01/11 16:07:44]

Done.

+};
+
+// Memory Infra service implements this interface. Clients register themselves
+// using the RegisterClient method and suggest a global memory dump using the
+// RequestGlobalMemoryDump method.
+interface Coordinator {
+  RegisterClient(Client client);
+  RequestGlobalMemoryDump(RequestArgs args) => (uint64 dump_guid, bool success);
+};