Use LatencyInfoSwapPromise to track LatencyInfo through compositor

cc/base/latency_info_swap_promise.cc

Index: cc/base/latency_info_swap_promise.cc
diff --git a/cc/base/latency_info_swap_promise.cc b/cc/base/latency_info_swap_promise.cc
new file mode 100644
index 0000000000000000000000000000000000000000..1f1cef48aae25945b33272ac4409f7c5f039eff3
--- /dev/null
+++ b/cc/base/latency_info_swap_promise.cc
@@ -0,0 +1,50 @@
+// Copyright 2013 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 "cc/base/latency_info_swap_promise.h"
+
+#include "base/logging.h"
+
+namespace {
+  ui::LatencyComponentType DidNotSwapReasonToLatencyComponentType(
+      cc::SwapPromise::DidNotSwapReason reason) {
+    switch (reason) {
+      case cc::SwapPromise::DID_NOT_SWAP_UNKNOWN:
+      case cc::SwapPromise::SWAP_FAILS:
+        return ui::INPUT_EVENT_LATENCY_TERMINATED_SWAP_FAILED_COMPONENT;
+      case cc::SwapPromise::COMMIT_FAILS:
+        return ui::INPUT_EVENT_LATENCY_TERMINATED_COMMIT_FAILED_COMPONENT;
+      case cc::SwapPromise::SWAP_PROMISE_LIST_OVERFLOW:
+        return ui::LATENCY_INFO_LIST_TERMINATED_OVERFLOW_COMPONENT;
+      default:
+        NOTREACHED() << "Unhandled DidNotSwapReason.";

[danakj, 2013/11/27 21:21:41]

Cool! OK, if this should be a notreached, can you move it below the switch and
delete the default: case, so we can get compiler errors here if a new
SwapPromise::DidNotSwapReason is added?

[Yufeng Shen (Slow to review), 2013/11/27 21:28:17]

Done.

+        break;
+    }
+    return ui::INPUT_EVENT_LATENCY_TERMINATED_SWAP_FAILED_COMPONENT;
+  }
+}  // namespace
+
+namespace cc {
+
+LatencyInfoSwapPromise::LatencyInfoSwapPromise(const ui::LatencyInfo& latency)
+    : latency_(latency) {
+}
+
+LatencyInfoSwapPromise::~LatencyInfoSwapPromise() {
+}
+
+void LatencyInfoSwapPromise::DidSwap(CompositorFrameMetadata* metadata) {
+  DCHECK(!latency_.terminated);
+  // TODO(mileus): Append the |latency_| into metadata's LatencyInfo list
+  // once we remove LatencyInfo merge in GPU side.
+  metadata->latency_info.MergeWith(latency_);
+}
+
+void LatencyInfoSwapPromise::DidNotSwap(DidNotSwapReason reason) {
+  latency_.AddLatencyNumber(DidNotSwapReasonToLatencyComponentType(reason),
+                            0, 0);
+  DCHECK(latency_.terminated);
+}
+
+}  // namespace cc