FBTF: Move the TabRestoreService::Observer into its own file.

chrome/browser/sessions/session_backend.cc

Index: chrome/browser/sessions/session_backend.cc
diff --git a/chrome/browser/sessions/session_backend.cc b/chrome/browser/sessions/session_backend.cc
index c06f81187963af90f225698a95ab3338502b1850..342c1f0498573ae0e2d946481ac80aec550e83e0 100644
--- a/chrome/browser/sessions/session_backend.cc
+++ b/chrome/browser/sessions/session_backend.cc
@@ -9,6 +9,7 @@
 #include "base/file_util.h"
 #include "base/histogram.h"
 #include "base/scoped_vector.h"
+#include "net/base/file_stream.h"
 
 using base::TimeTicks;
 
@@ -335,6 +336,9 @@ bool SessionBackend::AppendCommandsToFile(net::FileStream* file,
   return true;
 }
 
+SessionBackend::~SessionBackend() {
+}
+
 void SessionBackend::ResetFile() {
   DCHECK(inited_);
   if (current_session_file_.get()) {