Histogram to track missing and incomplete tiles

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index 1c62fb1f67eb2049582c01b2c5a92c18eb88a53a..372d1c7125b29322b5d3381c891b93ba6cea4800 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -222,6 +222,7 @@ LayerTreeHostImpl::LayerTreeHostImpl(
       wheel_scrolling_(false),
       scroll_affects_scroll_handler_(false),
       scroll_layer_id_when_mouse_over_scrollbar_(0),
+      is_scrolling_(false),
       tile_priorities_dirty_(false),
       root_layer_scroll_offset_delegate_(NULL),
       settings_(settings),
@@ -778,6 +779,9 @@ DrawResult LayerTreeHostImpl::CalculateRenderPasses(
 
   int layers_drawn = 0;
 
+  int num_missing_tiles = 0;
+  int num_incomplete_tiles = 0;
+
   const DrawMode draw_mode = GetDrawMode(output_surface_.get());
 
   LayerIteratorType end =
@@ -856,6 +860,7 @@ DrawResult LayerTreeHostImpl::CalculateRenderPasses(
         append_quads_data.approximated_visible_content_area);
 
     if (append_quads_data.num_missing_tiles) {
+      num_missing_tiles += append_quads_data.num_missing_tiles;
       bool layer_has_animating_transform =
           it->screen_space_transform_is_animating() ||
           it->draw_transform_is_animating();
@@ -864,6 +869,7 @@ DrawResult LayerTreeHostImpl::CalculateRenderPasses(
     }
 
     if (append_quads_data.had_incomplete_tile) {
+      num_incomplete_tiles += append_quads_data.num_incomplete_tiles;
       frame->contains_incomplete_tile = true;
       if (active_tree()->RequiresHighResToDraw())
         draw_result = DRAW_ABORTED_MISSING_HIGH_RES_CONTENT;
@@ -914,6 +920,13 @@ DrawResult LayerTreeHostImpl::CalculateRenderPasses(
   // If we're making a frame to draw, it better have at least one render pass.
   DCHECK(!frame->render_passes.empty());
 
+  if (is_scrolling_) {
+    UMA_HISTOGRAM_COUNTS("RenderPass.AppendQuadData.NumMissingTiles",
+                         num_missing_tiles);
+    UMA_HISTOGRAM_COUNTS_100("RenderPass.AppendQuadData.NumIncompleteTiles",
+                             num_incomplete_tiles);
+  }
+
   // Should only have one render pass in resourceless software mode.
   if (output_surface_->ForcedDrawToSoftwareDevice())
     DCHECK_EQ(1u, frame->render_passes.size());
@@ -2225,6 +2238,8 @@ InputHandler::ScrollStatus LayerTreeHostImpl::ScrollBegin(
     InputHandler::ScrollInputType type) {
   TRACE_EVENT0("cc", "LayerTreeHostImpl::ScrollBegin");
 
+  is_scrolling_ = true;

[danakj, 2014/07/03 16:01:45]

can you use the CurrentlyScrollingLayer() instead of adding a bool?

[weiliangc, 2014/07/04 21:35:53]

Done.

[weiliangc, 2014/07/04 21:35:53]

Using IsCurrentlyScrolling()

+
   if (top_controls_manager_)
     top_controls_manager_->ScrollBegin();
 
@@ -2551,6 +2566,7 @@ void LayerTreeHostImpl::ClearCurrentlyScrollingLayer() {
 }
 
 void LayerTreeHostImpl::ScrollEnd() {
+  is_scrolling_ = false;
   if (top_controls_manager_)
     top_controls_manager_->ScrollEnd();
   ClearCurrentlyScrollingLayer();