Add MemoryCoordinator

components/memory_coordinator/public/interfaces/child_memory_coordinator.mojom

Index: components/memory_coordinator/public/interfaces/child_memory_coordinator.mojom
diff --git a/components/memory_coordinator/public/interfaces/child_memory_coordinator.mojom b/components/memory_coordinator/public/interfaces/child_memory_coordinator.mojom
index 59c653ebcdb3f27d96432ced184d5ba93c7e7fe7..00abe8f547e5443c6d8f9eef7ee03a4ee0c67bba 100644
--- a/components/memory_coordinator/public/interfaces/child_memory_coordinator.mojom
+++ b/components/memory_coordinator/public/interfaces/child_memory_coordinator.mojom
@@ -19,4 +19,7 @@ interface ChildMemoryCoordinator {
   // Called when the central memory coodinator changes the state for child
   // processes.
   OnStateChange(MemoryState state);
+
+  // Returns the current memory state.
+  GetCurrentStateForTesting() => (MemoryState state);

[dcheng, 2016/07/12 05:20:28]

I think we shouldn't expose testing interfaces in the mojom if there are other
ways. This would be akin to adding an IPC just for testing purposes: it's
another IPC to audit for security and isn't something we want to encourage.

It looks like all the tests that use this can just use the impl directly
instead: I think doing that would make the tests simpler as well (since we don't
need to wait for all the callbacks to complete).

[bashi, 2016/07/12 05:51:46]

Maybe I'm wrong but I think we need an IPC to get information from impl class
because an instance of the impl class is in renderer and the test added in this
CL is a browsertest. Is there a way to access impl instances which live in a
renderer from a browsertest?

[dcheng, 2016/07/12 06:10:53]

Ah, I missed that it's a browser test. I think we still don't want to expose
test only IPCs if we can avoid it... as far as I know of, we only have 3 in
legacy IPC and it'd be good not to add another. Hmm...

[bashi, 2016/07/12 06:19:24]

I see. Let me think about a workaround. Probably we just check if there is a
mapping in the browser to test renderers create their ChildMemoryCoordinator.

[bashi, 2016/07/12 06:38:01]

Done. dcheng@, what do you think about PS#11?

 };