Move PageLoadTiming TimeDelta fields to a common header.

chrome/common/page_load_metrics/page_load_timing_fields.h

+// Copyright 2016 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.
+
+// All TimeDeltas are relative to navigation_start
+
+// Time that the first byte of the response is received.
+PAGE_LOAD_TIMING_TIME_DELTA_FIELD(response_start)
+
+// Time immediately before the DOMContentLoaded event is fired.
+PAGE_LOAD_TIMING_TIME_DELTA_FIELD(dom_content_loaded_event_start)
+
+// Time immediately before the load event is fired.
+PAGE_LOAD_TIMING_TIME_DELTA_FIELD(load_event_start)
+
+// Time when the first layout is completed.
+PAGE_LOAD_TIMING_TIME_DELTA_FIELD(first_layout)
+
+// Time when the first paint is performed.
+PAGE_LOAD_TIMING_TIME_DELTA_FIELD(first_paint)
+// Time when the first non-blank text is painted.
+PAGE_LOAD_TIMING_TIME_DELTA_FIELD(first_text_paint)
+// Time when the first image is painted.
+PAGE_LOAD_TIMING_TIME_DELTA_FIELD(first_image_paint)
+// Time when the first contentful thing (image, text, etc.) is painted.
+PAGE_LOAD_TIMING_TIME_DELTA_FIELD(first_contentful_paint)
+
+// Time that the document's parser started and stopped parsing main resource
+// content.
+PAGE_LOAD_TIMING_TIME_DELTA_FIELD(parse_start)
+PAGE_LOAD_TIMING_TIME_DELTA_FIELD(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
+// and parse_stop.
+PAGE_LOAD_TIMING_TIME_DELTA_FIELD(parse_blocked_on_script_load_duration)
+
+// Sum of times when the parser is blocked waiting on the load of a script
+// that was inserted from document.write. This duration must be less than or
+// equal to parse_blocked_on_script_load_duration. Note that this value may be
+// updated multiple times during the period between parse_start and
+// parse_stop. Note that some uncommon cases where scripts are loaded via
+// document.write are not currently covered by this field. See crbug/600711
+// for details.
+PAGE_LOAD_TIMING_TIME_DELTA_FIELD(
+    parse_blocked_on_script_load_from_document_write_duration)