Bug 1545239 - Move GetNodeDepth into ResizeObserver.cpp r=dholbert

GetNodeDepth() is a special version for ResizeObserver to get the depth
of node (across Shadow DOM). Based on the comment in D27615, it's better
to move it into ResizeObserver.cpp.

Differential Revision: https://phabricator.services.mozilla.com/D28736

--HG--
extra : moz-landing-system : lando

dom/base/ResizeObserver.cpp

@@ -7,13 +7,43 @@
 #include "mozilla/dom/ResizeObserver.h"
 
 #include "mozilla/dom/Document.h"
-#include "nsContentUtils.h"
+#include "nsIContent.h"
 #include "nsSVGUtils.h"
 #include <limits>
 
 namespace mozilla {
 namespace dom {
 
+/**
+ * Returns the length of the parent-traversal path (in terms of the number of
+ * nodes) to an unparented/root node from aNode. An unparented/root node is
+ * considered to have a depth of 1, its children have a depth of 2, etc.
+ * aNode is expected to be non-null.
+ * Note: The shadow root is not part of the calculation because the caller,
+ * ResizeObserver, doesn't observe the shadow root, and only needs relative
+ * depths among all the observed targets. In other words, we calculate the
+ * depth of the flattened tree.
+ *
+ * However, these is a spec issue about how to handle shadow DOM case. We
+ * may need to update this function later:
+ *   https://github.com/w3c/csswg-drafts/issues/3840
+ *
+ * https://drafts.csswg.org/resize-observer/#calculate-depth-for-node-h
+ */
+static uint32_t GetNodeDepth(nsINode* aNode) {
+  uint32_t depth = 1;
+
+  MOZ_ASSERT(aNode, "Node shouldn't be null");
+
+  // Use GetFlattenedTreeParentNode to bypass the shadow root and cross the
+  // shadow boundary to calculate the node depth without the shadow root.
+  while ((aNode = aNode->GetFlattenedTreeParentNode())) {
+    ++depth;
+  }
+
+  return depth;
+}
+
 NS_IMPL_CYCLE_COLLECTION(ResizeObservation, mTarget)
 NS_IMPL_CYCLE_COLLECTION_ROOT_NATIVE(ResizeObservation, AddRef)
 NS_IMPL_CYCLE_COLLECTION_UNROOT_NATIVE(ResizeObservation, Release)
@@ -136,7 +166,7 @@ void ResizeObserver::GatherActiveObservations(uint32_t aDepth) {
       continue;
     }
 
-    uint32_t targetDepth = nsContentUtils::GetNodeDepth(observation->Target());
+    uint32_t targetDepth = GetNodeDepth(observation->Target());
 
     if (targetDepth > aDepth) {
       mActiveTargets.AppendElement(observation);
@@ -172,7 +202,7 @@ uint32_t ResizeObserver::BroadcastActiveObservations() {
     // will be based on the updated size from last delivered observations.
     observation->UpdateBroadcastSize(rect.Size());
 
-    uint32_t targetDepth = nsContentUtils::GetNodeDepth(observation->Target());
+    uint32_t targetDepth = GetNodeDepth(observation->Target());
 
     if (targetDepth < shallowestTargetDepth) {
       shallowestTargetDepth = targetDepth;

dom/base/nsContentUtils.cpp

@@ -10524,21 +10524,6 @@ bool nsContentUtils::
          nsThreadManager::MainThreadHasPendingHighPriorityEvents();
 }
 
-/* static */
-uint32_t nsContentUtils::GetNodeDepth(nsINode* aNode) {
-  uint32_t depth = 1;
-
-  MOZ_ASSERT(aNode, "Node shouldn't be null");
-
-  // Use GetFlattenedTreeParentNode to bypass the shadow root and cross the
-  // shadow boundary to calculate the node depth without the shadow root.
-  while ((aNode = aNode->GetFlattenedTreeParentNode())) {
-    ++depth;
-  }
-
-  return depth;
-}
-
 /* static */
 bool nsContentUtils::IsURIInPrefList(nsIURI* aURI, const char* aPrefName) {
   MOZ_ASSERT(aPrefName);

dom/base/nsContentUtils.h

@@ -3256,24 +3256,6 @@ class nsContentUtils {
   static bool HighPriorityEventPendingForTopLevelDocumentBeforeContentfulPaint(
       Document* aDocument);
 
-  /**
-   * Returns the length of the parent-traversal path (in terms of the number of
-   * nodes) to an unparented/root node from aNode. An unparented/root node is
-   * considered to have a depth of 1, its children have a depth of 2, etc.
-   * aNode is expected to be non-null.
-   * Note: The shadow root is not part of the calculation because the caller,
-   * ResizeObserver, doesn't observe the shadow root, and only needs relative
-   * depths among all the observed targets. In other words, we calculate the
-   * depth of the flattened tree.
-   *
-   * However, these is a spec issue about how to handle shadow DOM case. We
-   * may need to update this function later:
-   *   https://github.com/w3c/csswg-drafts/issues/3840
-   *
-   * https://drafts.csswg.org/resize-observer/#calculate-depth-for-node-h
-   */
-  static uint32_t GetNodeDepth(nsINode* aNode);
-
  private:
   static bool InitializeEventTable();