compositor-worker: Remove code from cc_blink

third_party/WebKit/Source/platform/graphics/CompositorMutableStateProvider.cpp

+// 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 "platform/graphics/CompositorMutableStateProvider.h"
+
+#include "cc/layers/layer_impl.h"
+#include "cc/trees/layer_tree_impl.h"
+#include "platform/graphics/CompositorMutableState.h"
+#include "platform/graphics/CompositorMutation.h"
+#include "wtf/PassOwnPtr.h"
+
+namespace blink {
+
+CompositorMutableStateProvider::CompositorMutableStateProvider(cc::LayerTreeImpl* state, CompositorMutations* mutations)
+    : m_state(state)
+    , m_mutations(mutations)
+{
+}
+
+CompositorMutableStateProvider::~CompositorMutableStateProvider() {}
+
+PassOwnPtr<CompositorMutableState>
+CompositorMutableStateProvider::getMutableStateFor(uint64_t element_id)
+{
+    cc::LayerTreeImpl::ElementLayers layers = m_state->GetMutableLayers(element_id);
+
+    if (!layers.main && !layers.scroll)
+        return nullptr;
+
+    return adoptPtr(new CompositorMutableState(&m_mutations->map.find(element_id)->value, layers.main, layers.scroll));

[jbroman, 2016/01/18 21:40:26]

One caveat here: IIUC std::map guarantees that iterators (and
pointers/references) remain valid when other keys are inserted/removed, but
WTF::HashMap does not. Just want to confirm that is OK for your use.

[Ian Vollick, 2016/01/18 21:56:40]

Ah, right. No, this is a problem. I've gone back to std::map and added a
comment.

[Ian Vollick, 2016/01/19 14:49:30]

I remembered that Elliott had already suggested that we move this to a HashMap
in a previous CL, so I've switched this to a HashMap<uint64_t, OwnPtr<>>.

(Thanks also, Jeremy, for showing me how useful AddResults are.)

+}
+
+} // namespace blink