Remove PRODUCT_STRING_PATH from chrome_constants.h on Windows.

components/browser_watcher/exit_code_watcher_win.cc

Index: components/browser_watcher/exit_code_watcher_win.cc
diff --git a/components/browser_watcher/exit_code_watcher_win.cc b/components/browser_watcher/exit_code_watcher_win.cc
index 76aacd0e571c00f7ab16dd3241815f94a9fba935..3d762edaada74b643ec33cebc260ee7d04ca2b4c 100644
--- a/components/browser_watcher/exit_code_watcher_win.cc
+++ b/components/browser_watcher/exit_code_watcher_win.cc
@@ -24,9 +24,8 @@ base::string16 GetValueName(const base::Time creation_time,
 
 }  // namespace
 
-ExitCodeWatcher::ExitCodeWatcher(const base::char16* registry_path) :
-    registry_path_(registry_path), exit_code_(STILL_ACTIVE) {
-}
+ExitCodeWatcher::ExitCodeWatcher(base::StringPiece16 registry_path)
+    : registry_path_(registry_path.as_string()), exit_code_(STILL_ACTIVE) {}
 
 ExitCodeWatcher::~ExitCodeWatcher() {
 }