--- a/editor/libeditor/EditAction.h
+++ b/editor/libeditor/EditAction.h
@@ -60,18 +60,20 @@ enum class EditSubAction : int32_t
 
   // eComputeTextToOutput indicates to compute the editor value as plain text
   // or something requested format.
   eComputeTextToOutput,
 
   // eSetText indicates to set editor value to new value.
   eSetText,
 
-  // HTML editor only actions
-  insertBreak = 3000,
+  // eInsertParagraphSeparator indicates to insert paragraph separator, <br> or
+  // \n at least to break current line.
+  eInsertParagraphSeparator,
+
   makeList,
   indent,
   outdent,
   align,
   makeBasicBlock,
   removeList,
   makeDefListItem,
   insertElement,

--- a/editor/libeditor/HTMLEditRules.cpp
+++ b/editor/libeditor/HTMLEditRules.cpp
@@ -80,17 +80,17 @@ enum
 /********************************************************
  *  first some helpful functors we will use
  ********************************************************/
 
 static bool
 IsStyleCachePreservingSubAction(EditSubAction aEditSubAction)
 {
   return aEditSubAction == EditSubAction::eDeleteSelectedContent ||
-         aEditSubAction == EditSubAction::insertBreak ||
+         aEditSubAction == EditSubAction::eInsertParagraphSeparator ||
          aEditSubAction == EditSubAction::makeList ||
          aEditSubAction == EditSubAction::indent ||
          aEditSubAction == EditSubAction::outdent ||
          aEditSubAction == EditSubAction::align ||
          aEditSubAction == EditSubAction::makeBasicBlock ||
          aEditSubAction == EditSubAction::removeList ||
          aEditSubAction == EditSubAction::makeDefListItem ||
          aEditSubAction == EditSubAction::insertElement ||
@@ -534,17 +534,17 @@ HTMLEditRules::AfterEditInner(EditSubAct
     if (NS_WARN_IF(NS_FAILED(rv))) {
       return rv;
     }
 
     // attempt to transform any unneeded nbsp's into spaces after doing various operations
     if (aEditSubAction == EditSubAction::eInsertText ||
         aEditSubAction == EditSubAction::eInsertTextComingFromIME ||
         aEditSubAction == EditSubAction::eDeleteSelectedContent ||
-        aEditSubAction == EditSubAction::insertBreak ||
+        aEditSubAction == EditSubAction::eInsertParagraphSeparator ||
         aEditSubAction == EditSubAction::htmlPaste ||
         aEditSubAction == EditSubAction::loadHTML) {
       rv = AdjustWhitespace();
       if (NS_WARN_IF(NS_FAILED(rv))) {
         return rv;
       }
 
       // also do this for original selection endpoints.
@@ -570,17 +570,17 @@ HTMLEditRules::AfterEditInner(EditSubAct
         "Failed to pin selection to the new block");
       mNewBlock = nullptr;
     }
 
     // adjust selection for insert text, html paste, and delete actions
     if (aEditSubAction == EditSubAction::eInsertText ||
         aEditSubAction == EditSubAction::eInsertTextComingFromIME ||
         aEditSubAction == EditSubAction::eDeleteSelectedContent ||
-        aEditSubAction == EditSubAction::insertBreak ||
+        aEditSubAction == EditSubAction::eInsertParagraphSeparator ||
         aEditSubAction == EditSubAction::htmlPaste ||
         aEditSubAction == EditSubAction::loadHTML) {
       rv = AdjustSelection(aDirection);
       if (NS_WARN_IF(NS_FAILED(rv))) {
         return rv;
       }
     }
 
@@ -684,17 +684,17 @@ HTMLEditRules::WillDoAction(Selection* a
     case EditSubAction::eInsertText:
     case EditSubAction::eInsertTextComingFromIME:
       UndefineCaretBidiLevel();
       return WillInsertText(aInfo.mEditSubAction, aCancel, aHandled,
                             aInfo.inString, aInfo.outString,
                             aInfo.maxLength);
     case EditSubAction::loadHTML:
       return WillLoadHTML();
-    case EditSubAction::insertBreak:
+    case EditSubAction::eInsertParagraphSeparator:
       UndefineCaretBidiLevel();
       return WillInsertBreak(aCancel, aHandled);
     case EditSubAction::eDeleteSelectedContent:
       return WillDeleteSelection(aInfo.collapsedAction, aInfo.stripWrappers,
                                  aCancel, aHandled);
     case EditSubAction::makeList:
       return WillMakeList(aInfo.blockType, aInfo.entireList,
                           aInfo.bulletType, aCancel, aHandled);
@@ -753,17 +753,17 @@ HTMLEditRules::DidDoAction(Selection* aS
   if (NS_WARN_IF(!CanHandleEditAction())) {
     return NS_ERROR_EDITOR_DESTROYED;
   }
 
   AutoSafeEditorData setData(*this, *mHTMLEditor, *aSelection);
 
   switch (aInfo.mEditSubAction) {
     case EditSubAction::eInsertText:
-    case EditSubAction::insertBreak:
+    case EditSubAction::eInsertParagraphSeparator:
     case EditSubAction::eInsertTextComingFromIME:
       return NS_OK;
     case EditSubAction::eDeleteSelectedContent:
       return DidDeleteSelection();
     case EditSubAction::makeBasicBlock:
     case EditSubAction::indent:
     case EditSubAction::outdent:
     case EditSubAction::align:
@@ -7128,17 +7128,17 @@ HTMLEditRules::GetPromotedPoint(RulesEnd
                                 EditSubAction aEditSubAction)
 {
   MOZ_ASSERT(IsEditorDataAvailable());
 
   // we do one thing for text actions, something else entirely for other
   // actions
   if (aEditSubAction == EditSubAction::eInsertText ||
       aEditSubAction == EditSubAction::eInsertTextComingFromIME ||
-      aEditSubAction == EditSubAction::insertBreak ||
+      aEditSubAction == EditSubAction::eInsertParagraphSeparator ||
       aEditSubAction == EditSubAction::eDeleteText) {
     bool isSpace, isNBSP;
     nsCOMPtr<nsIContent> content =
       aNode.IsContent() ? aNode.AsContent() : nullptr;
     nsCOMPtr<nsIContent> temp;
     int32_t newOffset = aOffset;
     // for text actions, we want to look backwards (or forwards, as
     // appropriate) for additional whitespace or nbsp's.  We may have to act on
@@ -7377,17 +7377,17 @@ HTMLEditRules::PromoteRange(nsRange& aRa
         startOffset = 0;
         endOffset = block->Length();
       }
     }
   }
 
   if (aEditSubAction == EditSubAction::eInsertText ||
       aEditSubAction == EditSubAction::eInsertTextComingFromIME ||
-      aEditSubAction == EditSubAction::insertBreak ||
+      aEditSubAction == EditSubAction::eInsertParagraphSeparator ||
       aEditSubAction == EditSubAction::eDeleteText) {
      if (!startNode->IsContent() ||
          !endNode->IsContent()) {
        // GetPromotedPoint cannot promote node when action type is text
        // operation and selected node isn't content node.
        return;
      }
   }

--- a/editor/libeditor/HTMLEditor.cpp
+++ b/editor/libeditor/HTMLEditor.cpp
@@ -1150,17 +1150,18 @@ HTMLEditor::TabInTable(bool inIsShift,
   return NS_OK;
 }
 
 nsresult
 HTMLEditor::InsertBrElementAtSelectionWithTransaction()
 {
   // calling it text insertion to trigger moz br treatment by rules
   // XXX Why do we use EditSubAction::eInsertText here?  Looks like
-  //     EditSubAction::insertBreak or EditSubAction::eInsertNode is better.
+  //     EditSubAction::eInsertParagraphSeparator or EditSubAction::eInsertNode
+  //     is better.
   AutoTopLevelEditSubActionNotifier maybeTopLevelEditSubAction(
                                       *this, EditSubAction::eInsertText,
                                       nsIEditor::eNext);
 
   RefPtr<Selection> selection = GetSelection();
   NS_ENSURE_STATE(selection);
 
   if (!selection->IsCollapsed()) {

--- a/editor/libeditor/TextEditRules.cpp
+++ b/editor/libeditor/TextEditRules.cpp
@@ -322,17 +322,17 @@ TextEditRules::WillDoAction(Selection* a
 
   *aCancel = false;
   *aHandled = false;
 
   AutoSafeEditorData setData(*this, *mTextEditor, *aSelection);
 
   // my kingdom for dynamic cast
   switch (aInfo.mEditSubAction) {
-    case EditSubAction::insertBreak:
+    case EditSubAction::eInsertParagraphSeparator:
       UndefineCaretBidiLevel();
       return WillInsertBreak(aCancel, aHandled, aInfo.maxLength);
     case EditSubAction::eInsertText:
     case EditSubAction::eInsertTextComingFromIME:
       UndefineCaretBidiLevel();
       return WillInsertText(aInfo.mEditSubAction, aCancel, aHandled,
                             aInfo.inString, aInfo.outString,
                             aInfo.maxLength);

--- a/editor/libeditor/TextEditor.cpp
+++ b/editor/libeditor/TextEditor.cpp
@@ -1004,25 +1004,26 @@ TextEditor::InsertParagraphSeparatorAsAc
     return NS_ERROR_NOT_INITIALIZED;
   }
 
   // Protect the edit rules object from dying
   RefPtr<TextEditRules> rules(mRules);
 
   AutoPlaceholderBatch beginBatching(this);
   AutoTopLevelEditSubActionNotifier maybeTopLevelEditSubAction(
-                                      *this, EditSubAction::insertBreak,
+                                      *this,
+                                      EditSubAction::eInsertParagraphSeparator,
                                       nsIEditor::eNext);
 
   RefPtr<Selection> selection = GetSelection();
   if (NS_WARN_IF(!selection)) {
     return NS_ERROR_FAILURE;
   }
 
-  EditSubActionInfo subActionInfo(EditSubAction::insertBreak);
+  EditSubActionInfo subActionInfo(EditSubAction::eInsertParagraphSeparator);
   subActionInfo.maxLength = mMaxTextLength;
   bool cancel, handled;
   nsresult rv = rules->WillDoAction(selection, subActionInfo, &cancel, &handled);
   if (NS_WARN_IF(NS_FAILED(rv))) {
     // XXX DidDoAction() won't be called when WillDoAction() returns error.
     //     Perhaps, we should move the code between WillDoAction() and
     //     DidDoAction() to a new method and guarantee that DidDoAction() is
     //     always called after WillDoAction().