clang/win: Let remaining chromium_code targets build with -Wextra.

chrome/browser/shell_integration_win.cc

Index: chrome/browser/shell_integration_win.cc
diff --git a/chrome/browser/shell_integration_win.cc b/chrome/browser/shell_integration_win.cc
index 5de8cf594fd0de990384fa1462fad084432e9ac2..6ed09cfd9a7e39679c0849b0d99439bb2bd332b1 100644
--- a/chrome/browser/shell_integration_win.cc
+++ b/chrome/browser/shell_integration_win.cc
@@ -165,7 +165,7 @@ void MigrateChromiumShortcutsCallback() {
     }
   };
 
-  for (int i = 0; i < arraysize(kLocations); ++i) {
+  for (size_t i = 0; i < arraysize(kLocations); ++i) {
     base::FilePath path;
     if (!PathService::Get(kLocations[i].location_id, &path)) {
       NOTREACHED();