Reland: Composite fullscreen videos with composited descendants.

This one fixes
fullscreen/compositor-touch-hit-rects-fullscreen-video-controls.html.

It also modifies the test to actually verify that the video is
composited.

Bug: 1112884,1108972

Change-Id: Ia4357a540a3b8ac530331810824591af2210a5f2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2337544
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#795093}

third_party/blink/renderer/core/paint/compositing/compositing_requirements_updater.cc

@@ -27,6 +27,7 @@
 #include "third_party/blink/renderer/core/paint/compositing/compositing_requirements_updater.h"
 
 #include "base/macros.h"
+#include "third_party/blink/renderer/core/html/media/html_media_element.h"
 #include "third_party/blink/renderer/core/layout/layout_embedded_content.h"
 #include "third_party/blink/renderer/core/layout/layout_view.h"
 #include "third_party/blink/renderer/core/paint/compositing/paint_layer_compositor.h"
@@ -183,6 +184,13 @@ static CompositingReasons SubtreeReasonsForCompositing(
     subtree_reasons |= CompositingReason::kIsolateCompositedDescendants;
   }
 
+  if (layer->GetLayoutObject().IsVideo() &&
+      To<HTMLMediaElement>(layer->GetLayoutObject().GetNode())
+          ->IsFullscreen()) {
+    subtree_reasons |=
+        CompositingReason::kFullscreenVideoWithCompositedDescendants;
+  }
+
   // A layer with preserve-3d or perspective only needs to be composited if
   // there are descendant layers that will be affected by the preserve-3d or
   // perspective.

third_party/blink/renderer/platform/graphics/compositing_reasons.cc

@@ -104,6 +104,9 @@ constexpr CompositingReasonStringMap kCompositingReasonsStringMap[] = {
     {CompositingReason::kIsolateCompositedDescendants,
      "isolateCompositedDescendants",
      "Should isolate descendants to apply a blend effect"},
+    {CompositingReason::kFullscreenVideoWithCompositedDescendants,
+     "fullscreenVideoWithCompositedDescendants",
+     "Is a fullscreen video element with composited descendants"},
     {CompositingReason::kRoot, "root", "Is the root layer"},
     {CompositingReason::kLayerForHorizontalScrollbar,
      "layerForHorizontalScrollbar",

third_party/blink/renderer/platform/graphics/compositing_reasons.h

@@ -64,6 +64,7 @@ using CompositingReasons = uint64_t;
   V(PerspectiveWith3DDescendants)                                             \
   V(Preserve3DWith3DDescendants)                                              \
   V(IsolateCompositedDescendants)                                             \
+  V(FullscreenVideoWithCompositedDescendants)                                 \
                                                                               \
   /* The root layer is a special case. It may be forced to be a layer, but it \
   also needs to be a layer if anything else in the subtree is composited. */  \

third_party/blink/web_tests/FlagExpectations/composite-after-paint

@@ -65,3 +65,7 @@ http/tests/images/image-decode-in-frame.html [ Pass Failure ]
 # CompositeAfterPaint positions and scales root scrollbars incorrectly when
 # a page scale factor is applied.
 crbug.com/1106550 virtual/threaded-prefer-compositing/fast/scrolling/scrollbars/mouse-scrolling-on-div-scrollbar-thumb-scaled.html [ Failure ]
+
+# Need to force the video to be composited in this case, or change pre-CAP
+# to match CAP behavior.
+crbug.com/1108972 fullscreen/compositor-touch-hit-rects-fullscreen-video-controls.html [ Failure ]

third_party/blink/web_tests/fullscreen/compositor-touch-hit-rects-fullscreen-video-controls-expected.txt

@@ -11,6 +11,8 @@ handler: layer(800x600) has hit test rect (0,0 800x600)
 handler: layer(800x600) has hit test rect (0,0 800x600)
 handler: layer(800x600) has hit test rect (0,0 800x600)
 handler: layer(800x600) has hit test rect (0,0 800x600)
+handler: layer(800x600) has hit test rect (0,0 800x600)
 
+Found composited video layer, as expected
 END OF TEST
 

third_party/blink/web_tests/fullscreen/compositor-touch-hit-rects-fullscreen-video-controls.html

@@ -29,6 +29,11 @@ window.onload = function () {
         else
             consoleWrite("Should keep rect on document");
         logRects('handler');
+        if (JSON.parse(internals.layerTreeAsText(document)).layers.find(
+            layer => layer.name.includes("LayoutVideo")))
+          log('Found composited video layer, as expected')
+        else
+          log('ERROR: Failed to find composited video composited layer')
         endTest();
     });