FirstMeaningfulPaint UMA

chrome/common/page_load_metrics/page_load_timing.h

 // Copyright 2015 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 CHROME_COMMON_PAGE_LOAD_METRICS_PAGE_LOAD_TIMING_H_
 #define CHROME_COMMON_PAGE_LOAD_METRICS_PAGE_LOAD_TIMING_H_
 
 #include "base/optional.h"
 #include "base/time/time.h"
 #include "third_party/WebKit/public/platform/WebLoadingBehaviorFlag.h"
@@ skipping 34 matching lines @@
   base::Optional<base::TimeDelta> first_layout;
 
   // Time when the first paint is performed.
   base::Optional<base::TimeDelta> first_paint;
   // Time when the first non-blank text is painted.
   base::Optional<base::TimeDelta> first_text_paint;
   // Time when the first image is painted.
   base::Optional<base::TimeDelta> first_image_paint;
   // Time when the first contentful thing (image, text, etc.) is painted.
   base::Optional<base::TimeDelta> first_contentful_paint;
+  // Time when the page's primary content is painted.

[Charlie Harrison, 2016/08/04 02:18:29]

If this is experimental can you document that here?

[Kunihiko Sakamoto, 2016/08/04 02:56:14]

Done.

+  base::Optional<base::TimeDelta> first_meaningful_paint;
 
   // Time that the document's parser started and stopped parsing main resource
   // content.
   base::Optional<base::TimeDelta> parse_start;
   base::Optional<base::TimeDelta> parse_stop;
 
   // Sum of times when the parser is blocked waiting on the load of a script.
   // This duration takes place between parser_start and parser_stop, and thus
   // must be less than or equal to parser_stop - parser_start. Note that this
   // value may be updated multiple times during the period between parse_start
@@ skipping 17 matching lines @@
 struct PageLoadMetadata {
   PageLoadMetadata();
   bool operator==(const PageLoadMetadata& other) const;
   // These are packed blink::WebLoadingBehaviorFlag enums.
   int behavior_flags = blink::WebLoadingBehaviorNone;
 };
 
 }  // namespace page_load_metrics
 
 #endif  // CHROME_COMMON_PAGE_LOAD_METRICS_PAGE_LOAD_TIMING_H_