Ensure ResizeObserver fires on first observe()

If an element has the size 0x0, it won't yield an active observation
when the gather observation step is run.

Set the ResizeObservation::observation_size_ to -1x-1 in the constructor
to make sure we always produce an active observation for the element in
the first gather observation step it takes part in.

Fixed: 1128016
Change-Id: I61a077e5e74699f68a9c5230a980a5f5f0f973ae
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3970745
Reviewed-by: Dominic Farolino <dom@chromium.org>
Reviewed-by: Stefan Zager <szager@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/main@{#1067471}

content/browser/fenced_frame/fenced_frame_browsertest.cc

@@ -4474,14 +4474,8 @@ IN_PROC_BROWSER_TEST_P(FencedFrameParameterizedBrowserTest,
     ASSERT_TRUE(EvalJsAfterLifecycleUpdate(nodeA, "", "").error.empty());
 
     // Check that the inner size is what we expect.
-    // TODO(kojii|gtanzer): There is a known bug with the size 0,0,
-    // where the fenced frame can be resized once.
     int inner_width = EvalJs(nodeB, "innerWidth").ExtractInt();
     int inner_height = EvalJs(nodeB, "innerHeight").ExtractInt();
-    if (input_width == 0 && input_height == 0) {
-      output_width = 0;
-      output_height = 0;
-    }
     EXPECT_EQ(inner_width, output_width);
     EXPECT_EQ(inner_height, output_height);
 
@@ -4502,13 +4496,8 @@ IN_PROC_BROWSER_TEST_P(FencedFrameParameterizedBrowserTest,
     ASSERT_TRUE(EvalJsAfterLifecycleUpdate(nodeA, "", "").error.empty());
 
     // Check that the inner size hasn't changed.
-    // TODO(kojii|gtanzer): There is still a known bug with the size 0,0.
     inner_width = EvalJs(nodeB, "innerWidth").ExtractInt();
     inner_height = EvalJs(nodeB, "innerHeight").ExtractInt();
-    if (input_width == 0 && input_height == 0) {
-      output_width = new_width;
-      output_height = new_height;
-    }
     EXPECT_EQ(inner_width, output_width);
     EXPECT_EQ(inner_height, output_height);
   };

third_party/blink/renderer/core/html/fenced_frame/html_fenced_frame_element.cc

@@ -776,6 +776,10 @@ void HTMLFencedFrameElement::ResizeObserverDelegate::OnResize(
 }
 
 void HTMLFencedFrameElement::OnResize(const PhysicalRect& content_rect) {
+  // If we don't have a delegate, then we won't have a frame, so no reason to
+  // freeze.
+  if (!frame_delegate_)
+    return;
   if (frozen_frame_size_.has_value() && !size_set_after_freeze_) {
     // Only log this once per fenced frame.
     RecordFencedFrameResizedAfterSizeFrozen();

third_party/blink/renderer/core/resize_observer/resize_observation.cc

@@ -42,14 +42,18 @@ gfx::SizeF ComputeZoomAdjustedSVGBox(ResizeObserverBoxOptions box_option,
   }
 }
 
+// Set the initial observation size to something impossible so that the first
+// gather observation step always will pick up a new observation.
+constexpr LayoutSize kInitialObservationSize(-1, -1);
+
 }  // namespace
 
 ResizeObservation::ResizeObservation(Element* target,
                                      ResizeObserver* observer,
                                      ResizeObserverBoxOptions observed_box)
     : target_(target),
       observer_(observer),
-      observation_size_(0, 0),
+      observation_size_(kInitialObservationSize),
       observed_box_(observed_box) {
   DCHECK(target_);
 }

third_party/blink/web_tests/TestExpectations

@@ -3419,8 +3419,6 @@ crbug.com/626703 virtual/plz-dedicated-worker/external/wpt/fetch/api/abort/servi
 crbug.com/626703 external/wpt/avif/animated-avif-timeout.html [ Failure ]
 crbug.com/626703 [ Linux ] external/wpt/encoding/unsupported-labels.window.html [ Failure Timeout ]
 crbug.com/626703 [ Win ] external/wpt/encoding/unsupported-labels.window.html [ Failure Timeout ]
-crbug.com/626703 external/wpt/resize-observer/notify.html [ Timeout ]
-crbug.com/626703 external/wpt/resize-observer/svg.html [ Timeout ]
 crbug.com/626703 [ Win11 ] wpt_internal/geolocation-api/watchPosition-page-visibility.https.html [ Timeout ]
 crbug.com/626703 [ Mac11-arm64 ] external/wpt/fetch/api/redirect/redirect-upload.h2.any.sharedworker.html [ Timeout ]
 crbug.com/626703 [ Mac11-arm64 ] external/wpt/infrastructure/server/http2-context.sub.h2.any.html [ Timeout ]

third_party/blink/web_tests/external/wpt/css/css-sizing/contain-intrinsic-size/auto-006-expected.txt

@@ -1,7 +1,7 @@
 This is a testharness.js-based test.
 PASS Basic usage
-FAIL Last remembered size can be 0 assert_equals: Using last remembered size - clientWidth expected 0 but got 75
-FAIL Last remembered size can be set to 0 after losing display:none assert_equals: Using the new last remembered size - clientWidth expected 0 but got 100
+PASS Last remembered size can be 0
+PASS Last remembered size can be set to 0 after losing display:none
 PASS Last remembered size is logical
 PASS Last remembered size survives box destruction
 PASS Last remembered size survives display type changes
@@ -13,7 +13,7 @@ FAIL Lack of cis:auto during box creation removes last remembered size assert_eq
 FAIL Last remembered size can be removed synchronously assert_equals: Size containment with no last remembered size - clientWidth expected 1 but got 100
 PASS Disconnected element can briefly keep last remembered size
 FAIL Disconnected element ends up losing last remembered size assert_equals: Size containment with no last remembered size - clientWidth expected 1 but got 100
-FAIL Disconnected element ends up losing last remembered size even if size was 0x0 assert_equals: Size containment with no last remembered size - clientWidth expected 1 but got 100
+FAIL Disconnected element ends up losing last remembered size even if size was 0x0 assert_equals: Size containment with no last remembered size - clientWidth expected 1 but got 0
 FAIL Last remembered size survives becoming inline assert_equals: Still using previous last remembered size - clientWidth expected 100 but got 0
 PASS Last remembered size can be set to 0x0 after losing display:inline
 Harness: the test ran to completion.