Fix LatencyInfo compile error for ipc fuzzer

ui/events/latency_info.h

Index: ui/events/latency_info.h
diff --git a/ui/events/latency_info.h b/ui/events/latency_info.h
index 443e5fb9fbd6776be72fe7e9459ba7858492fca8..42c6b67360c892e492f2c6e55a0d0cc069c5ff1e 100644
--- a/ui/events/latency_info.h
+++ b/ui/events/latency_info.h
@@ -18,6 +18,11 @@
 #include "ipc/ipc_param_traits.h"
 #include "ui/events/events_base_export.h"
 
+namespace ipc_fuzzer {

[inferno, 2015/08/05 15:40:01]

We never sprinkle ipc fuzzer code in regular builds, so please remove changes in
this file.

[Yufeng Shen (Slow to review), 2015/08/05 16:08:24]

I copied from here 
https://code.google.com/p/chromium/codesearch#search/&q=%22friend%20struct%20...

guess it is better to clean those up ?

+template <class T>
+struct FuzzTraits;
+}  // namespace ipc_fuzzer
+
 namespace ui {
 
 enum LatencyComponentType {
@@ -212,6 +217,7 @@ class EVENTS_BASE_EXPORT LatencyInfo {
 
   FRIEND_TEST_ALL_PREFIXES(LatencyInfoParamTraitsTest, Basic);
   friend struct IPC::ParamTraits<ui::LatencyInfo>;
+  friend struct ipc_fuzzer::FuzzTraits<ui::LatencyInfo>;
 };
 
 }  // namespace ui