Hide RenderWidgetHostViewChildFrame if Occluded

The RenderWidgetHostView::WasOccluded and ~::WasUnOccluded are not overridden. On MacOSX minimizing
the browser leads to calling WebContents::WasOccluded which is therefore not triggering the
visibility of child RenderWidgets.

This CL implements the methods for RWHVCF and adds a test which verifies requestAnimationFrame is
throttled for occluded child renderer processes.

Bug: 903455
Change-Id: If836a872e6372abf31017cc81dcaa3e7d31d65b9
Reviewed-on: https://chromium-review.googlesource.com/c/1357303
Reviewed-by: Ken Buchanan <kenrb@chromium.org>
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Commit-Queue: Ehsan Karamad <ekaramad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#614162}

content/browser/renderer_host/render_widget_host_view_child_frame.cc

@@ -271,6 +271,14 @@ bool RenderWidgetHostViewChildFrame::IsShowing() {
   return !host()->is_hidden();
 }
 
+void RenderWidgetHostViewChildFrame::WasOccluded() {
+  Hide();
+}
+
+void RenderWidgetHostViewChildFrame::WasUnOccluded() {
+  Show();
+}
+
 gfx::Rect RenderWidgetHostViewChildFrame::GetViewBounds() const {
   gfx::Rect rect;
   if (frame_connector_) {

content/browser/renderer_host/render_widget_host_view_child_frame.h

@@ -98,6 +98,8 @@ class CONTENT_EXPORT RenderWidgetHostViewChildFrame
   void Show() override;
   void Hide() override;
   bool IsShowing() override;
+  void WasUnOccluded() override;
+  void WasOccluded() override;
   gfx::Rect GetViewBounds() const override;
   gfx::Size GetVisibleViewportSize() const override;
   void SetInsets(const gfx::Insets& insets) override;

content/browser/site_per_process_browsertest.cc

@@ -14488,4 +14488,50 @@ IN_PROC_BROWSER_TEST_F(SitePerProcessBrowserTest,
   EXPECT_FALSE(delete_a14.deleted());
 }
 
+#if !defined(OS_ANDROID)
+// This test verifies that after occluding a WebContents the RAF inside a
+// cross-process child frame is throttled.
+IN_PROC_BROWSER_TEST_F(SitePerProcessBrowserTest,
+                       OccludedRenderWidgetThrottlesRAF) {
+  GURL main_url(embedded_test_server()->GetURL(
+      "a.com", "/cross_site_iframe_factory.html?a(b)"));
+  EXPECT_TRUE(NavigateToURL(shell(), main_url));
+  FrameTreeNode* root = web_contents()->GetFrameTree()->root();
+  FrameTreeNode* subframe = root->child_at(0);
+  GURL page_with_raf_counter =
+      embedded_test_server()->GetURL("a.com", "/page_with_raf_counter.html");
+  NavigateFrameToURL(subframe, page_with_raf_counter);
+
+  // Initially page is visible - wait some time and then ensure a good number of
+  // rafs have been generated.
+  auto wait_for_half_a_second = []() {
+    base::RunLoop run_loop;
+    base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
+        FROM_HERE, run_loop.QuitClosure(),
+        base::TimeDelta::FromMilliseconds(500));
+    run_loop.Run();
+  };
+
+  ASSERT_TRUE(ExecuteScript(subframe, "reset_count();"));
+  wait_for_half_a_second();
+  int32_t default_raf_count = EvalJs(subframe, "raf_count").ExtractInt();
+  // On a 60 fps we should expect more than 30 counts - however purely for
+  // sanity checking and avoiding unnecessary flakes adding a comparison for a
+  // much lower value. This verifies that we did get *some* rAFs.
+  EXPECT_GT(default_raf_count, 5);
+  web_contents()->WasOccluded();
+  ASSERT_TRUE(ExecuteScript(subframe, "reset_count();"));
+  wait_for_half_a_second();
+  int32_t raf_count = EvalJs(subframe, "raf_count").ExtractInt();
+  // If the frame is throttled, we should expect 0 rAFs.
+  EXPECT_EQ(raf_count, 0);
+  // Sanity-check: unoccluding will reverse the effect.
+  web_contents()->WasShown();
+  ASSERT_TRUE(ExecuteScript(subframe, "reset_count();"));
+  wait_for_half_a_second();
+  ASSERT_TRUE(ExecuteScriptAndExtractInt(
+      subframe, "window.domAutomationController.send(raf_count)", &raf_count));
+  EXPECT_GT(raf_count, 5);
+}
+#endif
 }  // namespace content

content/browser/web_contents/web_contents_impl.cc

@@ -1451,8 +1451,10 @@ void WebContentsImpl::IncrementCapturerCount(const gfx::Size& capture_size) {
     // TODO(fdoray): Replace RenderWidgetHostView::WasUnOccluded() with a method
     // to explicitly notify the RenderWidgetHostView that capture began.
     // https://crbug.com/668690
-    for (RenderWidgetHostView* view : GetRenderWidgetHostViewsInTree())
-      view->WasUnOccluded();
+    if (auto* main_view = GetRenderWidgetHostView())
+      main_view->WasUnOccluded();
+    if (!ShowingInterstitialPage())
+      SetVisibilityForChildViews(true);
   }
 }
 
@@ -1729,8 +1731,13 @@ void WebContentsImpl::SetMainFrameImportance(
 
 void WebContentsImpl::WasOccluded() {
   if (!IsBeingCaptured()) {
-    for (RenderWidgetHostView* view : GetRenderWidgetHostViewsInTree())
-      view->WasOccluded();
+    if (auto* main_view = GetRenderWidgetHostView())
+      main_view->WasOccluded();
+    if (!ShowingInterstitialPage()) {
+      // Occluding child view is treated as hiding the view
+      // (https://crbug.com/903455).
+      SetVisibilityForChildViews(false);
+    }
   }
   SetVisibility(Visibility::OCCLUDED);
 }

content/test/data/page_with_raf_counter.html

@@ -0,0 +1,17 @@
+<!doctype html>
+<h1>This page contains a RAF loop and does some measurements of the interval</h1>
+<script>
+var recent_time_stamps = new Array(10);
+var raf_count = 0;
+
+function reset_count() {
+  raf_count = 0;
+}
+function on_raf(t) {
+  raf_count++;
+  recent_time_stamps.shift();
+  recent_time_stamps.push(t);
+  window.requestAnimationFrame(on_raf);
+}
+window.requestAnimationFrame(on_raf);
+</script>