Record "time to first text paint" UMA metrics in PageLoadHistograms

chrome/renderer/page_load_histograms.cc

Index: chrome/renderer/page_load_histograms.cc
diff --git a/chrome/renderer/page_load_histograms.cc b/chrome/renderer/page_load_histograms.cc
index b7fd03ec3cc5e3d03c096bf516a86d3c7a3e48d4..5d7669a3e5a537adcc2176c317cf34c55fa2d86e 100644
--- a/chrome/renderer/page_load_histograms.cc
+++ b/chrome/renderer/page_load_histograms.cc
@@ -252,6 +252,10 @@ void DumpHistograms(const WebPerformance& performance,
   Time load_event_end = Time::FromDoubleT(performance.loadEventEnd());
   Time begin = (request.is_null() ? navigation_start : request_start);
   Time first_paint = document_state->first_paint_time();
+  Time first_non_blank_text =
+      Time::FromDoubleT(performance.firstNonBlankText());
+  Time first_custom_font_text =
+      Time::FromDoubleT(performance.firstCustomFontText());
 
   DCHECK(!navigation_start.is_null());
 
@@ -597,6 +601,12 @@ void DumpHistograms(const WebPerformance& performance,
                     response_start - navigation_start);
     }
   }
+  if (!first_non_blank_text.is_null())
+    PLT_HISTOGRAM("PLT.BeginToFirstNonBlankText", first_non_blank_text - begin);
+  if (!first_custom_font_text.is_null()) {
+    PLT_HISTOGRAM("PLT.BeginToFirstCustomFontText",
+                  first_custom_font_text - begin);
+  }
 }
 
 // These histograms are based on the timing information collected in