Further reorganize code flow in ComputeInlineBoxPosition

This patch moves the atomic inline handling code before the block flow
handling code, so that there is no longer fall through from block flow
to atomic inline.

Bug: 771398
Change-Id: Idb4013e5616a2e81a13f4c6829c3afb2b86faa68
Reviewed-on: https://chromium-review.googlesource.com/775550
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#517766}

third_party/WebKit/Source/core/editing/InlineBoxPosition.cpp

@@ -283,50 +283,47 @@ InlineBoxPosition ComputeInlineBoxPositionTemplate(
                                                affinity, primary_direction);
   }
 
-  if (layout_object->IsLayoutBlockFlow()) {
-    if (CanHaveChildrenForEditing(anchor_node) &&
-        HasRenderedNonAnonymousDescendantsWithHeight(layout_object)) {
-      // Try a visually equivalent position with possibly opposite
-      // editability. This helps in case |this| is in an editable block
-      // but surrounded by non-editable positions. It acts to negate the
-      // logic at the beginning of
-      // |LayoutObject::createPositionWithAffinity()|.
-      const PositionTemplate<Strategy>& downstream_equivalent =
-          DownstreamIgnoringEditingBoundaries(position);
-      if (downstream_equivalent != position) {
-        return ComputeInlineBoxPosition(
-            downstream_equivalent, TextAffinity::kUpstream, primary_direction);
-      }
-      const PositionTemplate<Strategy>& upstream_equivalent =
-          UpstreamIgnoringEditingBoundaries(position);
-      if (upstream_equivalent == position ||
-          DownstreamIgnoringEditingBoundaries(upstream_equivalent) == position)
-        return InlineBoxPosition();
-
-      return ComputeInlineBoxPosition(
-          upstream_equivalent, TextAffinity::kUpstream, primary_direction);
-    }
-
-    // We can't return null here because atomic inlines can also be block flows,
-    // e.g., LayoutTextControl.
-    // TODO(xiaochengh): Move atomic inline handling before block flow handling
-    // so that we can directly return null here.
+  if (layout_object->IsAtomicInlineLevel()) {
+    // TODO(xiaochengh): Wrap the following into a function.
+    if (!layout_object->IsBox())
+      return InlineBoxPosition();
+    InlineBox* const inline_box =
+        ToLayoutBox(layout_object)->InlineBoxWrapper();
+    if (!inline_box)
+      return InlineBoxPosition();
+    if ((caret_offset > inline_box->CaretMinOffset() &&
+         caret_offset < inline_box->CaretMaxOffset()))
+      return InlineBoxPosition(inline_box, caret_offset);
+    return AdjustInlineBoxPositionForTextDirection(
+        inline_box, caret_offset, layout_object->Style()->GetUnicodeBidi(),
+        primary_direction);
   }
 
-  if (!layout_object->IsAtomicInlineLevel())
+  if (!layout_object->IsLayoutBlockFlow())
     return InlineBoxPosition();
-
-  if (!layout_object->IsBox())
+  // TODO(xiaochengh): Wrap the following into a function.
+  if (!CanHaveChildrenForEditing(anchor_node) ||
+      !HasRenderedNonAnonymousDescendantsWithHeight(layout_object))
     return InlineBoxPosition();
-  InlineBox* const inline_box = ToLayoutBox(layout_object)->InlineBoxWrapper();
-  if (!inline_box)
+  // Try a visually equivalent position with possibly opposite
+  // editability. This helps in case |this| is in an editable block
+  // but surrounded by non-editable positions. It acts to negate the
+  // logic at the beginning of
+  // |LayoutObject::createPositionWithAffinity()|.
+  const PositionTemplate<Strategy>& downstream_equivalent =
+      DownstreamIgnoringEditingBoundaries(position);
+  if (downstream_equivalent != position) {
+    return ComputeInlineBoxPosition(downstream_equivalent,
+                                    TextAffinity::kUpstream, primary_direction);
+  }
+  const PositionTemplate<Strategy>& upstream_equivalent =
+      UpstreamIgnoringEditingBoundaries(position);
+  if (upstream_equivalent == position ||
+      DownstreamIgnoringEditingBoundaries(upstream_equivalent) == position)
     return InlineBoxPosition();
-  if ((caret_offset > inline_box->CaretMinOffset() &&
-       caret_offset < inline_box->CaretMaxOffset()))
-    return InlineBoxPosition(inline_box, caret_offset);
-  return AdjustInlineBoxPositionForTextDirection(
-      inline_box, caret_offset, layout_object->Style()->GetUnicodeBidi(),
-      primary_direction);
+
+  return ComputeInlineBoxPosition(upstream_equivalent, TextAffinity::kUpstream,
+                                  primary_direction);
 }
 
 template <typename Strategy>