Use WebFrame::replaceMisspelledRange() to replace a misspelled range with text.

chrome/renderer/spellchecker/spellcheck_provider.cc

Index: chrome/renderer/spellchecker/spellcheck_provider.cc
===================================================================
--- chrome/renderer/spellchecker/spellcheck_provider.cc	(revision 142657)
+++ chrome/renderer/spellchecker/spellcheck_provider.cc	(working copy)
@@ -166,6 +166,7 @@
 bool SpellCheckProvider::OnMessageReceived(const IPC::Message& message) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(SpellCheckProvider, message)
+  IPC_MESSAGE_HANDLER(SpellCheckMsg_Replace, OnReplace)
 #if !defined(OS_MACOSX)
     IPC_MESSAGE_HANDLER(SpellCheckMsg_RespondSpellingService,
                         OnRespondSpellingService)
@@ -286,6 +287,12 @@
 #endif
 }
 
+void SpellCheckProvider::OnReplace(const string16& text) {
+  if (!render_view() || !render_view()->GetWebView())
+    return;
+  render_view()->GetWebView()->focusedFrame()->replaceMisspelledRange(text);
+}
+
 #if !defined(OS_MACOSX)
 void SpellCheckProvider::OnRespondSpellingService(
     int identifier,