clang/win: Fix a few warnings in targets not in chromium_builder_tests.

chrome/installer/gcapi/gcapi.h

Index: chrome/installer/gcapi/gcapi.h
diff --git a/chrome/installer/gcapi/gcapi.h b/chrome/installer/gcapi/gcapi.h
index a35293e3d5b8311a25f7fc9ba13e7b256bbb9bd0..81a59b5136a9efe27ffe66a4c8a98c70e417d2be 100644
--- a/chrome/installer/gcapi/gcapi.h
+++ b/chrome/installer/gcapi/gcapi.h
@@ -113,7 +113,7 @@ BOOL __stdcall CanOfferReactivation(const wchar_t* brand_code,
 // |shell_mode| should be set to one of GCAPI_INVOKED_STANDARD_SHELL or
 // GCAPI_INVOKED_UAC_ELEVATION depending on whether this method is invoked
 // from an elevated or non-elevated process.
-BOOL __stdcall ReactivateChrome(wchar_t* brand_code,
+BOOL __stdcall ReactivateChrome(const wchar_t* brand_code,
                                 int shell_mode,
                                 DWORD* error_code);