Refactor the loading tracking logic in WebContentsImpl.

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 5d0a34bd366fd3875a632891acc18ac624c64080..4ed01c15c021f5ea31dcb9ab36a5542a728fa885 100644
--- a/content/browser/frame_host/frame_tree_node.h
+++ b/content/browser/frame_host/frame_tree_node.h
@@ -30,6 +30,12 @@ class RenderFrameHostImpl;
 // are frame-specific (as opposed to page-specific).
 class CONTENT_EXPORT FrameTreeNode {
  public:
+  // These values indicate the loading progress status. The minimum progress

[Charlie Reis, 2015/02/20 23:42:12]

Hmm, I'm not thrilled about having these as public constants on FrameTreeNode,
since this class isn't primarily about loading.  I'm not sure I have a better
location to suggest, so maybe we can leave them here for now.

[Fabrice (no longer in Chrome), 2015/02/24 13:14:47]

We should be able to move these out of the class once the IPCs have been moved
to RFHI.

+  // value matches what Blink's ProgressTracker has traditionally used for a
+  // minimum progress value.
+  static double kNotStartedLoadingProgress;

[Charlie Reis, 2015/02/20 23:42:12]

static const double

Also, it would be clearer for LoadingProgress to be the prefix rather than
suffix (e.g., kLoadingProgressNotStarted).

[Fabrice (no longer in Chrome), 2015/02/23 20:02:06]

Done.

+  static double kMinimumLoadingProgress;
+  static double kDoneLoadingProgress;
 
   FrameTreeNode(FrameTree* frame_tree,
                 Navigator* navigator,
@@ -108,10 +114,17 @@ class CONTENT_EXPORT FrameTreeNode {
   void set_is_loading(bool is_loading) {
     is_loading_ = is_loading;
   }
+
   bool is_loading() const {
     return is_loading_;
   }
 
+  void set_loading_progress(double loading_progress) {
+    loading_progress_ = loading_progress;
+  }
+
+  double loading_progress() const { return loading_progress_; }
+
   RenderFrameHostImpl* current_frame_host() const {
     return render_manager_.current_frame_host();
   }
@@ -167,6 +180,9 @@ class CONTENT_EXPORT FrameTreeNode {
   // RenderFrameHost or using a counter to balance the events out.
   bool is_loading_;
 
+  // Double value representing the frame's completion progress (from 0 to 1).
+  double loading_progress_;
+
   DISALLOW_COPY_AND_ASSIGN(FrameTreeNode);
 };