Cleanup: Pull some browser keep alive functions into its own file.

chrome/browser/metro_viewer/chrome_metro_viewer_process_host_aurawin.h

Index: chrome/browser/metro_viewer/chrome_metro_viewer_process_host_aurawin.h
diff --git a/chrome/browser/metro_viewer/chrome_metro_viewer_process_host_aurawin.h b/chrome/browser/metro_viewer/chrome_metro_viewer_process_host_aurawin.h
index 26fae655c6c6cec2a362abfac1daf2a1bf1ebff2..7be0e3aabf1c4854e194b06586b0c106bc78fac2 100644
--- a/chrome/browser/metro_viewer/chrome_metro_viewer_process_host_aurawin.h
+++ b/chrome/browser/metro_viewer/chrome_metro_viewer_process_host_aurawin.h
@@ -5,12 +5,17 @@
 #ifndef CHROME_BROWSER_METRO_VIEWER_CHROME_METRO_VIEWER_PROCESS_HOST_AURAWIN_H_
 #define CHROME_BROWSER_METRO_VIEWER_CHROME_METRO_VIEWER_PROCESS_HOST_AURAWIN_H_
 
+#include "base/memory/scoped_ptr.h"
 #include "win8/viewer/metro_viewer_process_host.h"
 
 namespace base {
 class FilePath;
 }
 
+namespace browser_lifetime {
+class ScopedKeepAlive;
+}
+
 class ChromeMetroViewerProcessHost : public win8::MetroViewerProcessHost {
  public:
   ChromeMetroViewerProcessHost();
@@ -28,6 +33,8 @@ class ChromeMetroViewerProcessHost : public win8::MetroViewerProcessHost {
   void OnHandleSearchRequest(const base::string16& search_string) override;
   void OnWindowSizeChanged(uint32 width, uint32 height) override;
 
+  scoped_ptr<browser_lifetime::ScopedKeepAlive> keep_alive_;
+
   DISALLOW_COPY_AND_ASSIGN(ChromeMetroViewerProcessHost);
 };