Cleanup blink-side PlzNavigate logic

third_party/WebKit/Source/core/loader/DocumentLoader.h

Index: third_party/WebKit/Source/core/loader/DocumentLoader.h
diff --git a/third_party/WebKit/Source/core/loader/DocumentLoader.h b/third_party/WebKit/Source/core/loader/DocumentLoader.h
index ac5e7b73550fd341e906f5e24fdf942fbc32e069..0228b99f3afcab01864698f28bef2f98503641b3 100644
--- a/third_party/WebKit/Source/core/loader/DocumentLoader.h
+++ b/third_party/WebKit/Source/core/loader/DocumentLoader.h
@@ -134,6 +134,12 @@ class CORE_EXPORT DocumentLoader
     return m_state >= Committed && !m_dataReceived;
   }
 
+  // Without PlzNavigate, this is only true for a narrow window during
+  // navigation start. For PlzNavigate, a navigation sent to the browser will
+  // leave a dummy DocumentLoader in the NotStarted state until the navigation
+  // actually handled in the renderer.
+  bool didStart() const { return m_state != NotStarted; }
+
   void setSentDidFinishLoad() { m_state = SentDidFinishLoad; }
   bool sentDidFinishLoad() const { return m_state == SentDidFinishLoad; }