Add support for logging additional metrics in UKM.

components/ukm/ukm_source.h

Index: components/ukm/ukm_source.h
diff --git a/components/ukm/ukm_source.h b/components/ukm/ukm_source.h
index 854dd05337f0c8fe2db064290baa8cbfa7316910..a38ea0f6a7234352c30d55c4297e731d820f3702 100644
--- a/components/ukm/ukm_source.h
+++ b/components/ukm/ukm_source.h
@@ -8,6 +8,7 @@
 #include <stddef.h>
 
 #include "base/macros.h"
+#include "base/optional.h"
 #include "base/time/time.h"
 #include "url/gurl.h"
 
@@ -21,24 +22,44 @@ class UkmSource {
   UkmSource();
   ~UkmSource();
 
-  const GURL& committed_url() const { return committed_url_; }
-  void set_committed_url(const GURL& committed_url) {
-    committed_url_ = committed_url;
+  const GURL& url() const { return url_; }
+  void set_url(const GURL& url) { url_ = url; }
+
+  const base::Optional<base::TimeDelta>& parse_start() const {
+    return parse_start_;
+  }
+  void set_parse_start(base::TimeDelta parse_start) {
+    parse_start_ = parse_start;
   }
 
-  base::TimeDelta first_contentful_paint() const {
+  const base::Optional<base::TimeDelta>& first_contentful_paint() const {
     return first_contentful_paint_;
   }
   void set_first_contentful_paint(base::TimeDelta first_contentful_paint) {
     first_contentful_paint_ = first_contentful_paint;
   }
 
+  const base::Optional<base::TimeDelta>& first_meaningful_paint() const {
+    return first_meaningful_paint_;
+  }
+  void set_first_meaningful_paint(base::TimeDelta first_meaningful_paint) {
+    first_meaningful_paint_ = first_meaningful_paint;
+  }
+
+  const base::Optional<base::TimeDelta>& total_time() const {
+    return total_time_;
+  }
+  void set_total_time(base::TimeDelta total_time) { total_time_ = total_time; }
+
   // Serializes the members of the class into the supplied proto.
   void PopulateProto(Source* proto_source);
 
  private:
-  GURL committed_url_;
-  base::TimeDelta first_contentful_paint_;
+  GURL url_;
+  base::Optional<base::TimeDelta> parse_start_;
+  base::Optional<base::TimeDelta> first_contentful_paint_;
+  base::Optional<base::TimeDelta> first_meaningful_paint_;
+  base::Optional<base::TimeDelta> total_time_;
 
   DISALLOW_COPY_AND_ASSIGN(UkmSource);
 };