Create FrameNavigationEntries for the initial blank page in subframes.

content/browser/frame_host/frame_tree_node.h

Index: content/browser/frame_host/frame_tree_node.h
diff --git a/content/browser/frame_host/frame_tree_node.h b/content/browser/frame_host/frame_tree_node.h
index 6ad581abefc8a906ede0d5fa4ad3f8595d9aba98..94bd5d3773589c7551ed0ebdd675e3926e58ba8d 100644
--- a/content/browser/frame_host/frame_tree_node.h
+++ b/content/browser/frame_host/frame_tree_node.h
@@ -111,8 +111,13 @@ class CONTENT_EXPORT FrameTreeNode {
     return current_url_;
   }
 
-  void set_current_url(const GURL& url) {
-    current_url_ = url;
+  // Sets the last committed URL for this frame and updates
+  // has_committed_real_load accordingly.
+  void SetCurrentURL(const GURL& url);
+
+  // Returns true iff SetCurrentURL has been called with a non-blank URL.
+  bool has_committed_real_load() const {
+    return has_committed_real_load_;
   }
 
   // Set the current origin and notify proxies about the update.
@@ -241,12 +246,15 @@ class CONTENT_EXPORT FrameTreeNode {
   // The immediate children of this specific frame.
   ScopedVector<FrameTreeNode> children_;
 
-  // Track the current frame's last committed URL, so we can estimate the
-  // process impact of out-of-process iframes.
-  // TODO(creis): Remove this when we can store subframe URLs in the
-  // NavigationController.
+  // Track the current frame's last committed URL.
+  // TODO(creis): Consider storing a reference to the last committed
+  // FrameNavigationEntry here once those are created in all modes.
   GURL current_url_;
 
+  // Whether this frame has committed any real load, replacing its initial
+  // about:blank page.
+  bool has_committed_real_load_;
+
   // Track information that needs to be replicated to processes that have
   // proxies for this frame.
   FrameReplicationState replication_state_;