Move ProxyResolver to common.

HttpFetcher depends on it and HttpFetcher is in common.

Bug: 28171891
Test: mma
Change-Id: I1783821c4a7d6785ee23df1cde648a3e1ea8fadf
diff --git a/chrome_browser_proxy_resolver.h b/chrome_browser_proxy_resolver.h
index fcf85b6..10a55fb 100644
--- a/chrome_browser_proxy_resolver.h
+++ b/chrome_browser_proxy_resolver.h
@@ -24,7 +24,7 @@
 
 #include <base/memory/weak_ptr.h>
 
-#include "update_engine/proxy_resolver.h"
+#include "update_engine/common/proxy_resolver.h"
 
 namespace chromeos_update_engine {