Reland "[PM] Add FrameNode viewport intersection"

This reverts commit 53d410bb.

Reason for revert: There is a CL landed after this that changes a type somewhere, reverting is not that trivial

Original change's description:
> Revert "[PM] Add FrameNode viewport intersection"
>
> This reverts commit cf2a7489.
>
> Reason for revert:
> FrameNodeImplBrowserTest.ViewportIntersection_PartiallyVisible failing on CrOS
>  - example build: https://ci.chromium.org/p/chromium/builders/ci/linux-chromeos-rel/41947
>
> TBR=pmonette@chromium.org
>
> Original change's description:
> > [PM] Add FrameNode viewport intersection
> >
> > This CLs plumbs the viewport intersection to the FrameNode, which
> > will allow the tracking of the visibility of each frame.
> >
> > Bug: 1077217
> > Change-Id: Id2811b1c52e4fa3f3c449d1b32a1cb7084f82116
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2399621
> > Reviewed-by: François Doray <fdoray@chromium.org>
> > Reviewed-by: danakj <danakj@chromium.org>
> > Reviewed-by: Nasko Oskov <nasko@chromium.org>
> > Reviewed-by: David Bokan <bokan@chromium.org>
> > Commit-Queue: Patrick Monette <pmonette@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#816728}
>
> TBR=danakj@chromium.org,nasko@chromium.org,bokan@chromium.org,fdoray@chromium.org,pmonette@chromium.org
>
> Change-Id: I4e1cb014232b82016e14fbd85352a6442323300f
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: 1077217
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2470463
> Commit-Queue: Fabio Tirelo <ftirelo@chromium.org>
> Reviewed-by: Fabio Tirelo <ftirelo@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#817024}

TBR=danakj@chromium.org,nasko@chromium.org,fdoray@chromium.org,pmonette@chromium.org,ftirelo@chromium.org

# Not skipping CQ checks because this is a reland.

Bug: 1077217
Change-Id: I3c36272ac57b0857400331196a506069c596d36e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2471259Reviewed-by: Fabio Tirelo <ftirelo@chromium.org>
Commit-Queue: Fabio Tirelo <ftirelo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#817030}

chrome/browser/performance_manager/frame_node_impl_browsertest.cc

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/performance_manager/graph/frame_node_impl.h"
+
+#include "base/run_loop.h"
+#include "base/test/bind_test_util.h"
+#include "chrome/browser/ui/browser.h"
+#include "chrome/test/base/in_process_browser_test.h"
+#include "chrome/test/base/ui_test_utils.h"
+#include "components/performance_manager/graph/page_node_impl.h"
+#include "components/performance_manager/performance_manager_impl.h"
+#include "components/performance_manager/public/graph/page_node.h"
+#include "content/public/test/browser_test.h"
+#include "ui/gfx/geometry/rect.h"
+#include "ui/gfx/geometry/rect_conversions.h"
+#include "ui/gfx/geometry/rect_f.h"
+
+namespace performance_manager {
+
+namespace {
+
+class FrameNodeImplBrowserTest : public InProcessBrowserTest {
+ public:
+  FrameNodeImplBrowserTest() = default;
+  ~FrameNodeImplBrowserTest() override = default;
+};
+
+}  // namespace
+
+IN_PROC_BROWSER_TEST_F(FrameNodeImplBrowserTest,
+                       ViewportIntersection_OutOfView) {
+  ASSERT_TRUE(embedded_test_server()->Start());
+  EXPECT_EQ(1, browser()->tab_strip_model()->count());
+
+  const GURL main_frame_url(
+      embedded_test_server()->GetURL("/iframe_out_of_view.html"));
+
+  base::WeakPtr<PageNode> page_node =
+      PerformanceManager::GetPageNodeForWebContents(
+          browser()->tab_strip_model()->GetActiveWebContents());
+
+  // Navigate.
+  browser()->OpenURL(content::OpenURLParams(main_frame_url, content::Referrer(),
+                                            WindowOpenDisposition::CURRENT_TAB,
+                                            ui::PAGE_TRANSITION_TYPED, false));
+
+  // Ensure that loading is complete.
+  content::WaitForLoadStop(
+      browser()->tab_strip_model()->GetActiveWebContents());
+
+  // Verify that the viewport intersection has been set correctly on the graph.
+  base::RunLoop run_loop;
+  auto call_on_graph_cb = base::BindLambdaForTesting([&]() {
+    EXPECT_TRUE(page_node);
+    auto children = page_node.get()->GetMainFrameNode()->GetChildFrameNodes();
+    EXPECT_EQ(1U, children.size());
+    auto* iframe =
+        performance_manager::FrameNodeImpl::FromNode(*children.begin());
+    EXPECT_TRUE(iframe->viewport_intersection().IsEmpty());
+    run_loop.Quit();
+  });
+  PerformanceManager::CallOnGraph(FROM_HERE, call_on_graph_cb);
+  run_loop.Run();
+}
+
+IN_PROC_BROWSER_TEST_F(FrameNodeImplBrowserTest, ViewportIntersection_Hidden) {
+  ASSERT_TRUE(embedded_test_server()->Start());
+  EXPECT_EQ(1, browser()->tab_strip_model()->count());
+
+  const GURL main_frame_url(
+      embedded_test_server()->GetURL("/iframe_hidden.html"));
+
+  base::WeakPtr<PageNode> page_node =
+      PerformanceManager::GetPageNodeForWebContents(
+          browser()->tab_strip_model()->GetActiveWebContents());
+
+  // Navigate.
+  browser()->OpenURL(content::OpenURLParams(main_frame_url, content::Referrer(),
+                                            WindowOpenDisposition::CURRENT_TAB,
+                                            ui::PAGE_TRANSITION_TYPED, false));
+
+  // Ensure that loading is complete.
+  content::WaitForLoadStop(
+      browser()->tab_strip_model()->GetActiveWebContents());
+
+  // Verify that the viewport intersection has been set correctly on the graph.
+  base::RunLoop run_loop;
+  auto call_on_graph_cb = base::BindLambdaForTesting([&]() {
+    EXPECT_TRUE(page_node);
+    auto children = page_node.get()->GetMainFrameNode()->GetChildFrameNodes();
+    EXPECT_EQ(1U, children.size());
+    auto* iframe =
+        performance_manager::FrameNodeImpl::FromNode(*children.begin());
+    EXPECT_TRUE(iframe->viewport_intersection().IsEmpty());
+    run_loop.Quit();
+  });
+  PerformanceManager::CallOnGraph(FROM_HERE, call_on_graph_cb);
+  run_loop.Run();
+}
+
+IN_PROC_BROWSER_TEST_F(FrameNodeImplBrowserTest,
+                       ViewportIntersection_PartiallyVisible) {
+  ASSERT_TRUE(embedded_test_server()->Start());
+  EXPECT_EQ(1, browser()->tab_strip_model()->count());
+
+  const GURL main_frame_url(
+      embedded_test_server()->GetURL("/iframe_partially_visible.html"));
+
+  base::WeakPtr<PageNode> page_node =
+      PerformanceManager::GetPageNodeForWebContents(
+          browser()->tab_strip_model()->GetActiveWebContents());
+
+  // Navigate.
+  browser()->OpenURL(content::OpenURLParams(main_frame_url, content::Referrer(),
+                                            WindowOpenDisposition::CURRENT_TAB,
+                                            ui::PAGE_TRANSITION_TYPED, false));
+
+  // Ensure that loading is complete.
+  content::WaitForLoadStop(
+      browser()->tab_strip_model()->GetActiveWebContents());
+
+  // Verify that the viewport intersection has been set correctly on the graph.
+  base::RunLoop run_loop;
+  auto call_on_graph_cb = base::BindLambdaForTesting([&]() {
+    EXPECT_TRUE(page_node);
+    auto children = page_node.get()->GetMainFrameNode()->GetChildFrameNodes();
+    EXPECT_EQ(1U, children.size());
+    auto* iframe =
+        performance_manager::FrameNodeImpl::FromNode(*children.begin());
+
+    // The frame is a 100x100 px square centered on the origin of the viewport.
+    // Thus only the bottom right quarter is visible
+    const gfx::Rect kExpectedViewportIntersection(0, 0, 50, 50);
+    EXPECT_EQ(iframe->viewport_intersection(), kExpectedViewportIntersection);
+    run_loop.Quit();
+  });
+  PerformanceManager::CallOnGraph(FROM_HERE, call_on_graph_cb);
+  run_loop.Run();
+}
+
+IN_PROC_BROWSER_TEST_F(FrameNodeImplBrowserTest, ViewportIntersection_Scaled) {
+  ASSERT_TRUE(embedded_test_server()->Start());
+  EXPECT_EQ(1, browser()->tab_strip_model()->count());
+
+  const GURL main_frame_url(
+      embedded_test_server()->GetURL("/iframe_scaled.html"));
+
+  base::WeakPtr<PageNode> page_node =
+      PerformanceManager::GetPageNodeForWebContents(
+          browser()->tab_strip_model()->GetActiveWebContents());
+
+  // Navigate.
+  browser()->OpenURL(content::OpenURLParams(main_frame_url, content::Referrer(),
+                                            WindowOpenDisposition::CURRENT_TAB,
+                                            ui::PAGE_TRANSITION_TYPED, false));
+
+  // Ensure that loading is complete.
+  content::WaitForLoadStop(
+      browser()->tab_strip_model()->GetActiveWebContents());
+
+  // Verify that the viewport intersection has been set correctly on the graph.
+  base::RunLoop run_loop;
+  auto call_on_graph_cb = base::BindLambdaForTesting([&]() {
+    EXPECT_TRUE(page_node);
+    auto children = page_node.get()->GetMainFrameNode()->GetChildFrameNodes();
+    EXPECT_EQ(1U, children.size());
+    auto* iframe =
+        performance_manager::FrameNodeImpl::FromNode(*children.begin());
+
+    // The iframe is a 200x200 px square centered at (200, 200) scaled to 1.5x
+    // its size from it's center.
+
+    // The size should be 50% larger.
+    EXPECT_EQ(iframe->viewport_intersection().size(), gfx::Size(300, 300));
+
+    // Because the resulting square is still centered at (200, 200), its origin
+    // is (200-width/2, 200-height/2) = (50, 50)
+    EXPECT_EQ(iframe->viewport_intersection().origin(), gfx::Point(50, 50));
+
+    run_loop.Quit();
+  });
+  PerformanceManager::CallOnGraph(FROM_HERE, call_on_graph_cb);
+  run_loop.Run();
+}
+
+IN_PROC_BROWSER_TEST_F(FrameNodeImplBrowserTest, ViewportIntersection_Rotated) {
+  ASSERT_TRUE(embedded_test_server()->Start());
+  EXPECT_EQ(1, browser()->tab_strip_model()->count());
+
+  const GURL main_frame_url(
+      embedded_test_server()->GetURL("/iframe_rotated.html"));
+
+  base::WeakPtr<PageNode> page_node =
+      PerformanceManager::GetPageNodeForWebContents(
+          browser()->tab_strip_model()->GetActiveWebContents());
+
+  // Navigate.
+  browser()->OpenURL(content::OpenURLParams(main_frame_url, content::Referrer(),
+                                            WindowOpenDisposition::CURRENT_TAB,
+                                            ui::PAGE_TRANSITION_TYPED, false));
+
+  // Ensure that loading is complete.
+  content::WaitForLoadStop(
+      browser()->tab_strip_model()->GetActiveWebContents());
+
+  // Verify that the viewport intersection has been set correctly on the graph.
+  base::RunLoop run_loop;
+  auto call_on_graph_cb = base::BindLambdaForTesting([&]() {
+    EXPECT_TRUE(page_node);
+    auto children = page_node.get()->GetMainFrameNode()->GetChildFrameNodes();
+    EXPECT_EQ(1U, children.size());
+    auto* iframe =
+        performance_manager::FrameNodeImpl::FromNode(*children.begin());
+
+    // The iframe is a 100x100 px square centered at (150, 150) rotated by 45
+    // degree around its center.
+
+    // This results in a diamond shape also centered at (150, 150), whose width
+    // can be calculated with the pythagorean theorem.
+    const float width = sqrt(100 * 100 + 100 * 100);
+    const float start = 150 - width / 2;
+    const gfx::RectF enclosing_rectf(start, start, width, width);
+
+    // Thus the expectation for the viewport intersection is to be equal to the
+    // smallest Rect that encloses the |enclosing_rectf|.
+    const gfx::Rect expected_viewport_intersection =
+        ToEnclosingRect(enclosing_rectf);
+
+    EXPECT_EQ(iframe->viewport_intersection(), expected_viewport_intersection);
+
+    run_loop.Quit();
+  });
+  PerformanceManager::CallOnGraph(FROM_HERE, call_on_graph_cb);
+  run_loop.Run();
+}
+
+}  // namespace performance_manager

chrome/browser/ui/webui/discards/graph_dump_impl.h

@@ -105,6 +105,8 @@ class DiscardsGraphDumpImpl : public discards::mojom::GraphDump,
   void OnFirstContentfulPaint(
       const performance_manager::FrameNode* frame_node,
       base::TimeDelta time_since_navigation_start) override {}
+  void OnViewportIntersectionChanged(
+      const performance_manager::FrameNode* frame_node) override {}
 
   // PageNodeObserver implementation:
   void OnPageNodeAdded(const performance_manager::PageNode* page_node) override;

chrome/test/BUILD.gn

@@ -1168,6 +1168,7 @@ if (!is_android) {
       "../browser/pdf/pdf_extension_test_util.cc",
       "../browser/pdf/pdf_extension_test_util.h",
       "../browser/performance_manager/background_tab_loading_policy_browsertest.cc",
+      "../browser/performance_manager/frame_node_impl_browsertest.cc",
       "../browser/performance_manager/graph/page_node_impl_browsertest.cc",
       "../browser/performance_manager/mechanisms/page_discarder_browsertest.cc",
       "../browser/performance_manager/page_load_tracker_decorator_browsertest.cc",

chrome/test/data/iframe_hidden.html

+<html><head><title>iframe test</title></head>
+<body>
+<iframe src="title1.html" style="display:none;"></iframe>
+</body></html>

chrome/test/data/iframe_out_of_view.html

+<!DOCTYPE html>
+<html>
+<body>
+  <style>
+  body {
+    width: 100%;
+    height: 100%;
+    margin: 0;
+  }
+
+  iframe {
+    width: 400px;
+    height: 400px;
+    /* The size of the margin is bigger than the viewport */
+    margin: 300%;
+    border: 0;
+    padding: 0;
+    overflow: scroll;
+  }
+  </style>
+  <p> Single &lt;iframe&gt; which is positioned out of view. </p>
+  <iframe src="title1.html">
+  </iframe>
+  <p> Iframe should be positioned way above </p>
+</body>
+</html>

chrome/test/data/iframe_partially_visible.html

+<!DOCTYPE html>
+<html>
+  <style>
+    iframe {
+      position: absolute;
+      left: -50px;
+      top: -50px;
+      width: 100px;
+      height: 100px;
+      /* Removing external factor that might affect pixel accuracy */
+      border: none;
+      padding: 0;
+      margin: 0;
+    }
+  </style>
+  <iframe src="title1.html">
+  </iframe>
+</html>

chrome/test/data/iframe_rotated.html

+<!DOCTYPE html>
+<html>
+  <style>
+    iframe {
+      position: absolute;
+      left: 100px;
+      top: 100px;
+      width: 100px;
+      height: 100px;
+      transform: rotate(45deg);
+      /* Removing external factor that might affect pixel accuracy */
+      border: none;
+      padding: 0;
+      margin: 0;
+    }
+  </style>
+  <iframe src="title1.html">
+  </iframe>
+</html>

chrome/test/data/iframe_scaled.html

+<!DOCTYPE html>
+<html>
+  <style>
+    iframe {
+      position: absolute;
+      left: 100px;
+      top: 100px;
+      width: 200px;
+      height: 200px;
+      transform: scale(1.5);
+      /* Removing external factor that might affect pixel accuracy */
+      border: none;
+      padding: 0;
+      margin: 0;
+    }
+  </style>
+  <iframe src="title1.html">
+  </iframe>
+</html>

components/performance_manager/DEPS

@@ -14,4 +14,5 @@ include_rules = [
   "+third_party/blink/public/mojom/service_worker",
   "+third_party/blink/public/mojom/tokens",
   "+third_party/leveldatabase",
+  "+ui/gfx/geometry",
 ]

components/performance_manager/graph/frame_node_impl.cc

@@ -229,6 +229,13 @@ bool FrameNodeImpl::is_audible() const {
   return is_audible_.value();
 }
 
+const gfx::Rect& FrameNodeImpl::viewport_intersection() const {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+  // The viewport intersection of the main frame is not tracked.
+  DCHECK(!IsMainFrame());
+  return viewport_intersection_.value();
+}
+
 void FrameNodeImpl::SetIsCurrent(bool is_current) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   is_current_.SetAndMaybeNotify(this, is_current);
@@ -274,6 +281,14 @@ void FrameNodeImpl::SetIsAudible(bool is_audible) {
   is_audible_.SetAndMaybeNotify(this, is_audible);
 }
 
+void FrameNodeImpl::SetViewportIntersection(
+    const gfx::Rect& viewport_intersection) {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+  // The viewport intersection of the main frame is not tracked.
+  DCHECK(!IsMainFrame());
+  viewport_intersection_.SetAndMaybeNotify(this, viewport_intersection);
+}
+
 void FrameNodeImpl::OnNavigationCommitted(const GURL& url, bool same_document) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
 
@@ -497,6 +512,11 @@ bool FrameNodeImpl::IsAudible() const {
   return is_audible();
 }
 
+const gfx::Rect& FrameNodeImpl::GetViewportIntersection() const {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+  return viewport_intersection();
+}
+
 void FrameNodeImpl::AddChildFrame(FrameNodeImpl* child_frame_node) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   DCHECK(child_frame_node);

components/performance_manager/graph/frame_node_impl.h

@@ -82,6 +82,7 @@ class FrameNodeImpl
   void SetNetworkAlmostIdle() override;
   void SetLifecycleState(LifecycleState state) override;
   void SetHasNonEmptyBeforeUnload(bool has_nonempty_beforeunload) override;
+  void SetViewportIntersection(const gfx::Rect& viewport_intersection) override;
   void SetOriginTrialFreezePolicy(mojom::InterventionPolicy policy) override;
   void SetIsAdFrame() override;
   void SetHadFormInteraction() override;
@@ -120,6 +121,7 @@ class FrameNodeImpl
   const PriorityAndReason& priority_and_reason() const;
   bool had_form_interaction() const;
   bool is_audible() const;
+  const gfx::Rect& viewport_intersection() const;
 
   // Setters are not thread safe.
   void SetIsCurrent(bool is_current);
@@ -190,6 +192,7 @@ class FrameNodeImpl
   const PriorityAndReason& GetPriorityAndReason() const override;
   bool HadFormInteraction() const override;
   bool IsAudible() const override;
+  const gfx::Rect& GetViewportIntersection() const override;
 
   // Properties associated with a Document, which are reset when a
   // different-document navigation is committed in the frame.
@@ -336,6 +339,17 @@ class FrameNodeImpl
       NotifiesOnlyOnChanges<bool, &FrameNodeObserver::OnIsAudibleChanged>
           is_audible_{false};
 
+  // Tracks the intersection of this frame with the viewport.
+  //
+  // Note that the viewport intersection for the main frame is always invalid.
+  // This is because the main frame always occupies the entirety of the viewport
+  // so there is no point in tracking it. To avoid programming mistakes, it is
+  // forbidden to query this property for the main frame.
+  ObservedProperty::NotifiesOnlyOnChanges<
+      gfx::Rect,
+      &FrameNodeObserver::OnViewportIntersectionChanged>
+      viewport_intersection_;
+
   // Inline storage for ExecutionContext.
   std::unique_ptr<NodeAttachedData> execution_context_;
 

components/performance_manager/graph/frame_node_impl_describer.cc

@@ -6,6 +6,7 @@
 
 #include <sstream>
 #include <string>
+#include <utility>
 
 #include "base/task/task_traits.h"
 #include "base/values.h"
@@ -97,6 +98,8 @@ base::Value FrameNodeImplDescriber::DescribeFrameNodeData(
   ret.SetKey("priority",
              PriorityAndReasonToValue(impl->priority_and_reason_.value()));
   ret.SetBoolKey("is_audible", impl->is_audible_.value());
+  ret.SetStringKey("viewport_intersection",
+                   impl->viewport_intersection_.value().ToString());
 
   return ret;
 }

components/performance_manager/graph/frame_node_impl_unittest.cc

@@ -150,6 +150,7 @@ class LenientMockObserver : public FrameNodeImpl::Observer {
                void(const FrameNode*, const PriorityAndReason& previous_value));
   MOCK_METHOD1(OnHadFormInteractionChanged, void(const FrameNode*));
   MOCK_METHOD1(OnIsAudibleChanged, void(const FrameNode*));
+  MOCK_METHOD1(OnViewportIntersectionChanged, void(const FrameNode*));
   MOCK_METHOD1(OnNonPersistentNotificationCreated, void(const FrameNode*));
   MOCK_METHOD2(OnFirstContentfulPaint, void(const FrameNode*, base::TimeDelta));
 
@@ -367,6 +368,27 @@ TEST_F(FrameNodeImplTest, IsAudible) {
   graph()->RemoveFrameNodeObserver(&obs);
 }
 
+TEST_F(FrameNodeImplTest, ViewportIntersection) {
+  auto process = CreateNode<ProcessNodeImpl>();
+  auto page = CreateNode<PageNodeImpl>();
+  // A child frame node is used because the main frame does not have a viewport
+  // intersection.
+  auto main_frame_node = CreateFrameNodeAutoId(process.get(), page.get());
+  auto child_frame_node =
+      CreateFrameNodeAutoId(process.get(), page.get(), main_frame_node.get());
+
+  MockObserver obs;
+  graph()->AddFrameNodeObserver(&obs);
+
+  EXPECT_CALL(obs, OnViewportIntersectionChanged(child_frame_node.get()));
+
+  gfx::Rect kViewportIntersection(25, 25, 100, 100);
+  child_frame_node->SetViewportIntersection(kViewportIntersection);
+  EXPECT_EQ(child_frame_node->viewport_intersection(), kViewportIntersection);
+
+  graph()->RemoveFrameNodeObserver(&obs);
+}
+
 TEST_F(FrameNodeImplTest, FirstContentfulPaint) {
   auto process = CreateNode<ProcessNodeImpl>();
   auto page = CreateNode<PageNodeImpl>();
@@ -386,7 +408,10 @@ TEST_F(FrameNodeImplTest, PublicInterface) {
   auto process = CreateNode<ProcessNodeImpl>();
   auto page = CreateNode<PageNodeImpl>();
   auto frame_node = CreateFrameNodeAutoId(process.get(), page.get());
+  auto child_frame_node =
+      CreateFrameNodeAutoId(process.get(), page.get(), frame_node.get());
   const FrameNode* public_frame_node = frame_node.get();
+  const FrameNode* public_child_frame_node = child_frame_node.get();
 
   // Simply test that the public interface impls yield the same result as their
   // private counterpart.
@@ -427,6 +452,10 @@ TEST_F(FrameNodeImplTest, PublicInterface) {
             public_frame_node->IsHoldingIndexedDBLock());
   EXPECT_EQ(frame_node->had_form_interaction(),
             public_frame_node->HadFormInteraction());
+  // Use the child frame node to test the viewport intersection because the
+  // viewport intersection of the main frame is not tracked.
+  EXPECT_EQ(child_frame_node->viewport_intersection(),
+            public_child_frame_node->GetViewportIntersection());
 }
 
 TEST_F(FrameNodeImplTest, VisitChildFrameNodes) {

components/performance_manager/public/graph/frame_node.h

@@ -13,6 +13,7 @@
 #include "components/performance_manager/public/mojom/coordination_unit.mojom.h"
 #include "components/performance_manager/public/mojom/lifecycle.mojom.h"
 #include "third_party/blink/public/common/tokens/tokens.h"
+#include "ui/gfx/geometry/rect.h"
 
 class GURL;
 
@@ -173,6 +174,9 @@ class FrameNode : public Node {
   // Returns true if the frame is audible, false otherwise.
   virtual bool IsAudible() const = 0;
 
+  // Returns the intersection of this frame with the viewport.
+  virtual const gfx::Rect& GetViewportIntersection() const = 0;
+
   // Returns a proxy to the RenderFrameHost associated with this node. The
   // proxy may only be dereferenced on the UI thread.
   virtual const RenderFrameHostProxy& GetRenderFrameHostProxy() const = 0;
@@ -240,6 +244,9 @@ class FrameNodeObserver {
   // Invoked when the IsAudible property changes.
   virtual void OnIsAudibleChanged(const FrameNode* frame_node) = 0;
 
+  // Invoked when a frame's intersection with the viewport changes
+  virtual void OnViewportIntersectionChanged(const FrameNode* frame_node) = 0;
+
   // Events with no property changes.
 
   // Invoked when a non-persistent notification has been issued by the frame.
@@ -287,6 +294,7 @@ class FrameNode::ObserverDefaultImpl : public FrameNodeObserver {
       const PriorityAndReason& previous_value) override {}
   void OnHadFormInteractionChanged(const FrameNode* frame_node) override {}
   void OnIsAudibleChanged(const FrameNode* frame_node) override {}
+  void OnViewportIntersectionChanged(const FrameNode* frame_node) override {}
   void OnNonPersistentNotificationCreated(
       const FrameNode* frame_node) override {}
   void OnFirstContentfulPaint(

components/performance_manager/public/mojom/BUILD.gn

@@ -15,5 +15,8 @@ mojom_component("mojom") {
     "lifecycle.mojom",
   ]
 
-  public_deps = [ "//mojo/public/mojom/base" ]
+  public_deps = [
+    "//mojo/public/mojom/base",
+    "//ui/gfx/geometry/mojom",
+  ]
 }

components/performance_manager/public/mojom/coordination_unit.mojom

@@ -7,6 +7,7 @@ module performance_manager.mojom;
 import "mojo/public/mojom/base/process_id.mojom";
 import "mojo/public/mojom/base/time.mojom";
 import "components/performance_manager/public/mojom/lifecycle.mojom";
+import "ui/gfx/geometry/mojom/geometry.mojom";
 
 // Any new type here needs to be mirrored between coordination_unit_types.h and
 // coordination_unit.mojom, and have mappings between the two defined in
@@ -37,6 +38,7 @@ interface DocumentCoordinationUnit {
   SetNetworkAlmostIdle();
   SetLifecycleState(LifecycleState state);
   SetHasNonEmptyBeforeUnload(bool has_nonempty_beforeunload);
+
   // Called the first time a form in this document is interacted with.
   SetHadFormInteraction();
 
@@ -48,6 +50,11 @@ interface DocumentCoordinationUnit {
 
   SetIsAdFrame();
 
+  // Called when the intersection between this frame and the viewport changes.
+  // The viewport is the rectangular area of the top-level document that is
+  // visible. This is used to drive the frame prioritization logic.
+  SetViewportIntersection(gfx.mojom.Rect viewport_intersection);
+
   // Event signals.
 
   // Called when the associated frame has caused a non-persistent notification

third_party/blink/renderer/core/frame/local_frame_view.cc

@@ -151,6 +151,7 @@
 #include "third_party/blink/renderer/platform/graphics/paint/paint_chunk_subset_recorder.h"
 #include "third_party/blink/renderer/platform/graphics/paint/paint_controller.h"
 #include "third_party/blink/renderer/platform/instrumentation/histogram.h"
+#include "third_party/blink/renderer/platform/instrumentation/resource_coordinator/document_resource_coordinator.h"
 #include "third_party/blink/renderer/platform/instrumentation/tracing/trace_event.h"
 #include "third_party/blink/renderer/platform/instrumentation/tracing/traced_value.h"
 #include "third_party/blink/renderer/platform/language.h"

third_party/blink/renderer/platform/instrumentation/resource_coordinator/document_resource_coordinator.cc

@@ -50,6 +50,11 @@ void DocumentResourceCoordinator::SetHasNonEmptyBeforeUnload(
   service_->SetHasNonEmptyBeforeUnload(has_nonempty_beforeunload);
 }
 
+void DocumentResourceCoordinator::SetViewportIntersection(
+    const gfx::Rect& viewport_intersection) {
+  service_->SetViewportIntersection(viewport_intersection);
+}
+
 void DocumentResourceCoordinator::SetOriginTrialFreezePolicy(
     InterventionPolicy policy) {
   service_->SetOriginTrialFreezePolicy(policy);

third_party/blink/renderer/platform/instrumentation/resource_coordinator/document_resource_coordinator.h

@@ -29,6 +29,7 @@ class PLATFORM_EXPORT DocumentResourceCoordinator final {
   void SetNetworkAlmostIdle();
   void SetLifecycleState(performance_manager::mojom::LifecycleState);
   void SetHasNonEmptyBeforeUnload(bool has_nonempty_beforeunload);
+  void SetViewportIntersection(const gfx::Rect& viewport_intersection);
   void SetOriginTrialFreezePolicy(
       performance_manager::mojom::InterventionPolicy policy);
   // A one way switch that marks a frame as being an adframe.