DRAFT CL: Add FrameNavigationEntry and track subframe session histories.

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 458887baaf6403ba538c8775fadf7fbf695e1ba6..0c5bb60f991a9a258dce7e962eceafdfc61119d5 100644
--- a/content/browser/frame_host/frame_tree_node.h
+++ b/content/browser/frame_host/frame_tree_node.h
@@ -11,6 +11,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
+#include "content/browser/frame_host/frame_navigation_entry.h"
 #include "content/browser/frame_host/render_frame_host_impl.h"
 #include "content/browser/frame_host/render_frame_host_manager.h"
 #include "content/common/content_export.h"
@@ -84,12 +85,19 @@ class CONTENT_EXPORT FrameTreeNode {
     return children_[index];
   }
 
-  const GURL& current_url() const {
-    return current_url_;
+  FrameNavigationEntry* last_committed_frame_entry() {
+    return last_committed_frame_entry_.get();
+  }
+
+  void set_last_committed_frame_entry(FrameNavigationEntry* entry) {
+    last_committed_frame_entry_ = entry;
   }
 
-  void set_current_url(const GURL& url) {
-    current_url_ = url;
+  // TODO(creis): Rename to last_committed_url().
+  const GURL& current_url() const {
+    if (last_committed_frame_entry_)
+      return last_committed_frame_entry_->url();
+    return GURL::EmptyGURL();
   }
 
   void set_current_origin(const url::Origin& origin) {
@@ -158,11 +166,9 @@ 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.
-  GURL current_url_;
+  // Track the current frame's last committed FrameNavigationEntry, which lets
+  // other callers know what the last committed URL is.
+  scoped_refptr<FrameNavigationEntry> last_committed_frame_entry_;
 
   // Track information that needs to be replicated to processes that have
   // proxies for this frame.