Add MemoryCoordinator

components/memory_coordinator/child/blink_memory_coordinator_client.cc

+// 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.
+
+#include "components/memory_coordinator/child/blink_memory_coordinator_client.h"
+
+#include "third_party/WebKit/public/platform/Platform.h"
+#include "third_party/WebKit/public/web/WebMemoryCoordinator.h"
+
+namespace memory_coordinator {
+
+BlinkMemoryCoordinatorClient::BlinkMemoryCoordinatorClient() {}
+
+BlinkMemoryCoordinatorClient::~BlinkMemoryCoordinatorClient() {}
+
+void BlinkMemoryCoordinatorClient::OnMemoryStateChange(
+    mojom::MemoryState state) {
+  if (!blink::Platform::current()) {
+    return;
+  }
+
+  switch (state) {
+    case mojom::MemoryState::NORMAL:
+      blink::WebMemoryCoordinator::setAllocationMode(

[haraken, 2016/06/27 02:17:07]

As commented in the other place, I want to make the Blink API consistent with
MemoryCoordinatorClient's API. So I'd prefer just redirecting the
OnMemoryStateChanged API to Blink instead of translating it to setAllocationMode
or something.

[bashi, 2016/06/27 03:49:29]

That requires duplicate enums in public/web which I don't want to introduce.
We'll end up translating the enum to actual actions and I think this is an
appropriate boundary.

[haraken, 2016/06/27 04:48:33]

But you're already introducing WebMemoryAllocationMode::Normal etc? I don't
think we can avoid duplicating the enum.

A couple of questions:

- Are you going to add a purging mode to setAllocationMode?

- Are you going to add setAllocationMode to all clients (cc, skia, v8 etc)?

- What's a difference between "onMemoryStateChanged" and "setAllocationMode"?

[bashi, 2016/06/27 06:36:46]

It's not going to be the same as mojom::MemoryState. I don't plan to add Purge
enum. Instead, I'll add purge() (or similar) API in WebMemoryCoordinator.
No, as described above.
No. I may do similar things but if ethese components already provide APIs for
purging/throttling I'll just use it.
The former is notification, the later is action.

At some point we need to have swich or if statements to convert notification to
action, and I think mc -> blink boundary would be a good place to do that.

+          blink::WebMemoryAllocationMode::Normal);
+      break;
+    case mojom::MemoryState::THROTTLED:
+      blink::WebMemoryCoordinator::setAllocationMode(
+          blink::WebMemoryAllocationMode::Throttled);
+      break;
+    case mojom::MemoryState::UNKNOWN:
+    default:
+      LOG(WARNING) << "Unrecognized memory state: " << state;
+  }
+}
+
+}  // namespace memory_coordinator