SF: Introduce DisplaySnapshot

DisplaySnapshot stores the immutable state of a physical display,
captured on hotplug. The SurfaceFlinger class stores a map from
PhysicalDisplayId to PhysicalDisplay, a new class that augments
this state with the sp<DisplayToken>.

Later, DisplayDevice will be removed, and SF::mDisplays will map
wp<DisplayToken> to compositionengine::Display.

Bug: 241285876
Test: libsurfaceflinger_unittest
Test: dumpsys SurfaceFlinger --displays
Change-Id: I172df87c4a7a9cf64659ff9cfbd6df195ee4bc8d
diff --git a/services/surfaceflinger/Display/PhysicalDisplay.h b/services/surfaceflinger/Display/PhysicalDisplay.h
new file mode 100644
index 0000000..cba1014
--- /dev/null
+++ b/services/surfaceflinger/Display/PhysicalDisplay.h
@@ -0,0 +1,76 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <functional>
+#include <utility>
+
+#include <binder/IBinder.h>
+#include <ui/DisplayId.h>
+#include <utils/StrongPointer.h>
+
+#include "DisplayMap.h"
+#include "DisplaySnapshot.h"
+
+namespace android::display {
+
+// TODO(b/229877597): Replace with AIDL type.
+using DisplayToken = IBinder;
+
+class PhysicalDisplay {
+public:
+    template <typename... Args>
+    PhysicalDisplay(sp<DisplayToken> token, Args&&... args)
+          : mToken(std::move(token)), mSnapshot(std::forward<Args>(args)...) {}
+
+    PhysicalDisplay(const PhysicalDisplay&) = delete;
+    PhysicalDisplay(PhysicalDisplay&&) = default;
+
+    const sp<DisplayToken>& token() const { return mToken; }
+    const DisplaySnapshot& snapshot() const { return mSnapshot; }
+
+    // Transformers for PhysicalDisplays::get.
+
+    using SnapshotRef = std::reference_wrapper<const DisplaySnapshot>;
+    SnapshotRef snapshotRef() const { return std::cref(mSnapshot); }
+
+    bool isInternal() const {
+        return mSnapshot.connectionType() == ui::DisplayConnectionType::Internal;
+    }
+
+    // Predicate for ftl::find_if on PhysicalDisplays.
+    static constexpr auto hasToken(const sp<DisplayToken>& token) {
+        return [&token](const std::pair<const PhysicalDisplayId, PhysicalDisplay>& pair) {
+            return pair.second.token() == token;
+        };
+    }
+
+private:
+    const sp<DisplayToken> mToken;
+
+    // Effectively const except in move constructor.
+    DisplaySnapshot mSnapshot;
+};
+
+using PhysicalDisplays = PhysicalDisplayMap<PhysicalDisplayId, PhysicalDisplay>;
+
+// Combinator for ftl::Optional<PhysicalDisplayId>::and_then.
+constexpr auto getPhysicalDisplay(const PhysicalDisplays& displays) {
+    return [&](PhysicalDisplayId id) { return displays.get(id); };
+}
+
+} // namespace android::display