cc: Throttle tile priority updates to once a frame.

cc/layer_tree_host_impl.cc

Index: cc/layer_tree_host_impl.cc
diff --git a/cc/layer_tree_host_impl.cc b/cc/layer_tree_host_impl.cc
index c0b3c7dcc0c09e2127101a6f9b6d1e397ba0eb58..f8c27f622b841e91886139270bfaabe96a22a660 100644
--- a/cc/layer_tree_host_impl.cc
+++ b/cc/layer_tree_host_impl.cc
@@ -194,7 +194,7 @@ void LayerTreeHostImpl::commitComplete()
     // more lazily when needed prior to drawing.
     if (m_settings.implSidePainting) {
         pendingTree()->set_needs_update_draw_properties();
-        pendingTree()->UpdateDrawProperties();
+        pendingTree()->UpdateDrawProperties(LayerTreeImpl::UPDATE_PENDING_TREE);
     } else {
         activeTree()->set_needs_update_draw_properties();
     }
@@ -651,7 +651,7 @@ bool LayerTreeHostImpl::prepareToDraw(FrameData& frame)
 
     if (m_topControlsManager)
         m_topControlsManager->UpdateDrawPositions();
-    activeTree()->UpdateDrawProperties();
+    activeTree()->UpdateDrawProperties(LayerTreeImpl::UPDATE_ACTIVE_TREE_FOR_DRAW);
 
     frame.renderSurfaceLayerList = &activeTree()->RenderSurfaceLayerList();
     frame.renderPasses.clear();
@@ -935,7 +935,7 @@ void LayerTreeHostImpl::activatePendingTreeIfNeeded()
     if (!pendingTree())
         return;
 
-    pendingTree()->UpdateDrawProperties();
+    pendingTree()->UpdateDrawProperties(LayerTreeImpl::UPDATE_PENDING_TREE);
 
     // It's always fine to activate to an empty tree.  Otherwise, only
     // activate once all visible resources in pending tree are ready.
@@ -1158,7 +1158,7 @@ void LayerTreeHostImpl::setNeedsRedraw()
 
 bool LayerTreeHostImpl::ensureRenderSurfaceLayerList()
 {
-    activeTree()->UpdateDrawProperties();
+    activeTree()->UpdateDrawProperties(LayerTreeImpl::UPDATE_ACTIVE_TREE);
     return activeTree()->RenderSurfaceLayerList().size();
 }