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 bc1e5d3ff5c8991b26873dad183d20a34f2c1f0b..caa44f8693dd6a932d4be75e4686330e720a8d73 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 false 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
+  // is actually handled in the renderer.
+  bool didStart() const { return m_state != NotStarted; }
+
   void setSentDidFinishLoad() { m_state = SentDidFinishLoad; }
   bool sentDidFinishLoad() const { return m_state == SentDidFinishLoad; }