customtabs: Send time to first contentful paint to the caller.

chrome/chrome_browser.gypi

Index: chrome/chrome_browser.gypi
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index fd74b4fed82267d7a6f54ae05eba1a5b2383d224..cdf926940dbe428a186e9f535ff97c82b74d1256 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -1042,6 +1042,8 @@
       'browser/net/spdyproxy/data_reduction_promo_infobar_delegate_android.h',
       'browser/net/spdyproxy/data_reduction_proxy_settings_android.cc',
       'browser/net/spdyproxy/data_reduction_proxy_settings_android.h',
+      'browser/page_load_metrics/observers/android_page_load_metrics_observer.cc',
+      'browser/page_load_metrics/observers/android_page_load_metrics_observer.h',
       'browser/password_manager/account_chooser_dialog_android.cc',
       'browser/password_manager/account_chooser_dialog_android.h',
       'browser/password_manager/auto_signin_first_run_dialog_android.cc',
@@ -2021,6 +2023,7 @@
       'android/java/src/org/chromium/chrome/browser/mojo/ChromeServiceRegistrar.java',
       'android/java/src/org/chromium/chrome/browser/infobar/DownloadOverwriteInfoBar.java',
       'android/java/src/org/chromium/chrome/browser/infobar/TranslateInfoBar.java',
+      'android/java/src/org/chromium/chrome/browser/metrics/PageLoadMetrics.java',
       'android/java/src/org/chromium/chrome/browser/metrics/UmaSessionStats.java',
       'android/java/src/org/chromium/chrome/browser/metrics/UmaUtils.java',
       'android/java/src/org/chromium/chrome/browser/metrics/VariationsSession.java',