Adding DRP specfic UMA for FirstContentfulPaint

chrome/chrome_browser.gypi

Index: chrome/chrome_browser.gypi
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index 95dc97ed0c73cc9a947cd9ee1b95b8a3080ca2a3..6617321a6f283ab9d37dcc2ac0502dc3c9583541 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -399,20 +399,22 @@
       'browser/mod_pagespeed/mod_pagespeed_metrics.h',
       'browser/native_window_notification_source.h',
       'browser/net/predictor_tab_helper.cc',
       'browser/net/predictor_tab_helper.h',
       'browser/ntp_snippets/ntp_snippets_service_factory.cc',
       'browser/ntp_snippets/ntp_snippets_service_factory.h',
       'browser/page_load_metrics/observers/aborts_page_load_metrics_observer.cc',
       'browser/page_load_metrics/observers/aborts_page_load_metrics_observer.h',
       'browser/page_load_metrics/observers/core_page_load_metrics_observer.cc',
       'browser/page_load_metrics/observers/core_page_load_metrics_observer.h',
+      'browser/page_load_metrics/observers/data_reduction_proxy_metrics_observer.cc',
+      'browser/page_load_metrics/observers/data_reduction_proxy_metrics_observer.h',
       'browser/page_load_metrics/observers/document_write_page_load_metrics_observer.cc',
       'browser/page_load_metrics/observers/document_write_page_load_metrics_observer.h',
       'browser/page_load_metrics/observers/from_gws_page_load_metrics_observer.cc',
       'browser/page_load_metrics/observers/from_gws_page_load_metrics_observer.h',
       'browser/page_load_metrics/observers/google_captcha_observer.cc',
       'browser/page_load_metrics/observers/google_captcha_observer.h',
       'browser/page_load_metrics/observers/service_worker_page_load_metrics_observer.cc',
       'browser/page_load_metrics/observers/service_worker_page_load_metrics_observer.h',
       'browser/page_load_metrics/observers/stale_while_revalidate_metrics_observer.cc',
       'browser/page_load_metrics/observers/stale_while_revalidate_metrics_observer.h',
@@ -518,20 +520,22 @@
       'browser/push_messaging/push_messaging_service_impl.cc',
       'browser/push_messaging/push_messaging_service_impl.h',
       'browser/push_messaging/push_messaging_service_observer.cc',
       'browser/push_messaging/push_messaging_service_observer.h',
       'browser/push_messaging/push_messaging_service_observer_android.cc',
       'browser/push_messaging/push_messaging_service_observer_android.h',
       'browser/renderer_context_menu/context_menu_content_type_factory.cc',
       'browser/renderer_context_menu/context_menu_content_type_factory.h',
       'browser/renderer_context_menu/context_menu_content_type_panel.cc',
       'browser/renderer_context_menu/context_menu_content_type_panel.h',
+      'browser/renderer_host/chrome_navigation_data.cc',
+      'browser/renderer_host/chrome_navigation_data.h',
       'browser/renderer_host/chrome_render_message_filter.cc',
       'browser/renderer_host/chrome_render_message_filter.h',
       'browser/renderer_host/chrome_render_widget_host_view_mac_delegate.h',
       'browser/renderer_host/chrome_render_widget_host_view_mac_delegate.mm',
       'browser/renderer_host/chrome_render_widget_host_view_mac_history_swiper.h',
       'browser/renderer_host/chrome_render_widget_host_view_mac_history_swiper.mm',
       'browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc',
       'browser/renderer_host/chrome_resource_dispatcher_host_delegate.h',
       'browser/renderer_host/thread_hop_resource_throttle.cc',
       'browser/renderer_host/thread_hop_resource_throttle.h',