Introduce InsertIncrementalTextCommand to respect existing style for composition

third_party/WebKit/Source/core/editing/commands/TypingCommand.h

Index: third_party/WebKit/Source/core/editing/commands/TypingCommand.h
diff --git a/third_party/WebKit/Source/core/editing/commands/TypingCommand.h b/third_party/WebKit/Source/core/editing/commands/TypingCommand.h
index 6f57268ed3d375ddb165bcc831128904096fe8d7..cb6964a7a66220a9ddc1f1b4fd8ecfd2678e2b96 100644
--- a/third_party/WebKit/Source/core/editing/commands/TypingCommand.h
+++ b/third_party/WebKit/Source/core/editing/commands/TypingCommand.h
@@ -75,13 +75,31 @@ class TypingCommand final : public CompositeEditCommand {
                          const VisibleSelection&,
                          Options,
                          TextCompositionType = TextCompositionNone);
+
+  // When the IME only wants to change a few characters of the composition, only
+  // touch those characters in order to preserve rich text substructure.
+  static void insertIncrementalText(Document&,
+                                    const String&,
+                                    const String&,
+                                    Options,
+                                    TextCompositionType = TextCompositionNone);
+  static void insertIncrementalText(Document&,
+                                    const String&,
+                                    const String&,
+                                    const VisibleSelection&,
+                                    Options,
+                                    TextCompositionType = TextCompositionNone);
   static bool insertLineBreak(Document&);
   static bool insertParagraphSeparator(Document&);
   static bool insertParagraphSeparatorInQuotedContent(Document&);
   static void closeTyping(LocalFrame*);
 
-  void insertText(const String& text, bool selectInsertedText, EditingState*);
-  void insertTextRunWithoutNewlines(const String& text,
+  void insertText(const String& textToInsert,
+                  const String& textForEvent,
+                  bool selectInsertedText,
+                  EditingState*);
+  void insertTextRunWithoutNewlines(const String& textToInsert,
+                                    const String& textForEvent,
                                     bool selectInsertedText,
                                     EditingState*);
   void insertLineBreak(EditingState*);
@@ -156,8 +174,23 @@ class TypingCommand final : public CompositeEditCommand {
     m_commandType = typingCommand;
   }
 
+  static void setSelectionForIncrementalInsertion(TypingCommand*,
+                                                  const VisibleSelection&,
+                                                  LocalFrame*);
+  static void setCommandSelectionForIncrementalInsertion(
+      TypingCommand*,
+      const VisibleSelection&,
+      LocalFrame*);
+
   ETypingCommand m_commandType;
+
+  // The text to be inserted.
   String m_textToInsert;
+  // The text used to send 'input' event. It could be different with
+  // |m_textToInsert| when applying incremental insertion. In other situations,
+  // they're the same.
+  String m_textForEvent;
+
   bool m_openForMoreTyping;
   bool m_selectInsertedText;
   bool m_smartDelete;
@@ -173,6 +206,8 @@ class TypingCommand final : public CompositeEditCommand {
 
   bool m_shouldRetainAutocorrectionIndicator;
   bool m_shouldPreventSpellChecking;
+
+  static bool m_isIncrementalInsertion;
 };
 
 DEFINE_TYPE_CASTS(TypingCommand,