Queue latency info swap promises in a separate already-active queue.

cc/output/swap_promise.h

 // 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.
 
 #ifndef CC_OUTPUT_SWAP_PROMISE_H_
 #define CC_OUTPUT_SWAP_PROMISE_H_
 
 #include "cc/output/compositor_frame_metadata.h"
 
 namespace cc {
@@ skipping 43 matching lines @@
   virtual void DidActivate() = 0;
   virtual void DidSwap(CompositorFrameMetadata* metadata) = 0;
   virtual void DidNotSwap(DidNotSwapReason reason) = 0;
   // This is called when the main thread starts a (blocking) commit
   virtual void OnCommit() {}
 
   // A non-zero trace id identifies a trace flow object that is embedded in the
   // swap promise. This can be used for registering additional flow steps to
   // visualize the object's path through the system.
   virtual int64 TraceId() const = 0;
+
+  static std::string DidNotSwapReasonToString(DidNotSwapReason reason) {

[Sami, 2015/08/18 11:19:18]

Is this used anywhere?

nit: this could just be a const char*

[Tobias Sargeant, 2015/08/18 13:39:52]

It isn't. It was useful during debugging the unittest, and I figured it was
useful to keep around. Upon reflection, I've removed it.

+    switch (reason) {
+      case SWAP_FAILS:
+        return "SWAP_FAILS";
+      case COMMIT_FAILS:
+        return "COMMIT_FAILS";
+      case COMMIT_NO_UPDATE:
+        return "COMMIT_NO_UPDATE";
+      case ACTIVATION_FAILS:
+        return "ACTIVATION_FAILS";
+      default:
+        NOTREACHED();
+        return "";
+    }
+  }
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_SWAP_PROMISE_H_