Performance Manager: Treat occluded pages as not visible

Bug: 668690
Change-Id: Iac624c067336b2f2479a6541a5d2fc7566f4dd5e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1603065Reviewed-by: François Doray <fdoray@chromium.org>
Commit-Queue: Patrick Monette <pmonette@chromium.org>
Cr-Commit-Position: refs/heads/master@{#659137}

chrome/browser/performance_manager/performance_manager_tab_helper.cc

@@ -297,8 +297,7 @@ void PerformanceManagerTabHelper::OnMainFrameNavigation(int64_t navigation_id) {
 
 void PerformanceManagerTabHelper::UpdatePageNodeVisibility(
     content::Visibility visibility) {
-  // TODO(fdoray): An OCCLUDED tab should not be considered visible.
-  const bool is_visible = visibility != content::Visibility::HIDDEN;
+  const bool is_visible = visibility == content::Visibility::VISIBLE;
   PostToGraph(FROM_HERE, &PageNodeImpl::SetIsVisible, page_node_.get(),
               is_visible);
 }