Switch LatencyInfo struct to use a map.

cc/debug/latency_info.h

Index: cc/debug/latency_info.h
diff --git a/cc/debug/latency_info.h b/cc/debug/latency_info.h
index 1e75db8f93b8c051d24bc761baf3f39873867915..99cd5104672089f6dabb03d96e1c8e64af1d6b07 100644
--- a/cc/debug/latency_info.h
+++ b/cc/debug/latency_info.h
@@ -5,23 +5,36 @@
 #ifndef CC_DEBUG_LATENCY_INFO_H_
 #define CC_DEBUG_LATENCY_INFO_H_
 
+#include <map>
+#include <utility>
+
 #include "base/time.h"
+#include "cc/base/cc_export.h"
 
 namespace cc {
 
-struct LatencyInfo {
-  int64 renderer_main_frame_number;
-  int64 renderer_impl_frame_number;
-  int64 browser_main_frame_number;
-  int64 browser_impl_frame_number;
+enum LatencyComponent {
+  kRendererMainThread,
+  kRendererImplThread,
+  kBrowserMainThread,
+  kBrowserImplThread,
+  kInputEvent,
+};
+
+struct CC_EXPORT LatencyInfo {
+  // Map a Latency Component (with an int64 id) to a number representing what
+  // events have happened in that component.
+  typedef std::map<std::pair<LatencyComponent, int64>, int64> LatencyMap;
+
+  LatencyMap latency_numbers;
 
   base::TimeTicks swap_timestamp;
 
-  LatencyInfo() :
-      renderer_main_frame_number(0),
-      renderer_impl_frame_number(0),
-      browser_main_frame_number(0),
-      browser_impl_frame_number(0) {}
+  LatencyInfo() {}
+
+  void MergeWith(const LatencyInfo& other);
+
+  void AddLatencyNumber(LatencyComponent component, int64 id, int64 number);
 };
 
 }  // namespace cc