First step of porting VisitedLinkMaster to POSIX:

chrome/browser/renderer_host/browser_render_process_host.cc

Index: chrome/browser/renderer_host/browser_render_process_host.cc
diff --git a/chrome/browser/renderer_host/browser_render_process_host.cc b/chrome/browser/renderer_host/browser_render_process_host.cc
index a93cbbe861370a364535de2a37436cac5f0e47ba..307cfe0fe6ea80e22798e7952e0edeb1ebdd65d9 100644
--- a/chrome/browser/renderer_host/browser_render_process_host.cc
+++ b/chrome/browser/renderer_host/browser_render_process_host.cc
@@ -27,12 +27,23 @@
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/cache_manager_host.h"
 #include "chrome/browser/extensions/user_script_master.h"
+#if defined(OS_WIN)
 #include "chrome/browser/history/history.h"
+#else
+// TODO(port): remove scaffolding, use history.h for both POSIX and WIN.
+#include "chrome/common/temp_scaffolding_stubs.h"
+#endif  // !defined(OS_WIN)
+
 #include "chrome/browser/plugin_service.h"
 #include "chrome/browser/renderer_host/render_widget_helper.h"
 #include "chrome/browser/renderer_host/renderer_security_policy.h"
 #include "chrome/browser/resource_message_filter.h"
+#if defined(OS_WIN)
 #include "chrome/browser/spellchecker.h"
+#else
+// TODO(port): remove scaffolding, use history.h for both POSIX and WIN.
+#include "chrome/common/temp_scaffolding_stubs.h"
+#endif  // !defined(OS_WIN)
 #include "chrome/browser/visitedlink_master.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
@@ -470,11 +481,17 @@ void BrowserRenderProcessHost::WidgetHidden() {
 }
 
 void BrowserRenderProcessHost::AddWord(const std::wstring& word) {
+#if defined(OS_MACOSX)
+  // TODO(port): reimplement when we get the spell checker up and running on
+  // OS X.
+  NOTIMPLEMENTED();
+#else
   base::Thread* io_thread = g_browser_process->io_thread();
   if (profile()->GetSpellChecker()) {
     io_thread->message_loop()->PostTask(FROM_HERE, NewRunnableMethod(
         profile()->GetSpellChecker(), &SpellChecker::AddWord, word));
   }
+#endif // !defined(OS_MACOSX)
 }
 
 base::ProcessHandle BrowserRenderProcessHost::GetRendererProcessHandle() {