CHECK XPS initialization succeeds on Windows.

printing/backend/print_backend_win.cc

Index: printing/backend/print_backend_win.cc
diff --git a/printing/backend/print_backend_win.cc b/printing/backend/print_backend_win.cc
index 7a657142f5934f136abd79b41d587a9cfc297729..ac29e6715885a72282f95033150e1547acee3445 100644
--- a/printing/backend/print_backend_win.cc
+++ b/printing/backend/print_backend_win.cc
@@ -11,6 +11,7 @@
 #include <memory>
 
 #include "base/memory/free_deleter.h"
+#include "base/memory/ptr_util.h"
 #include "base/numerics/safe_conversions.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_piece.h"
@@ -187,7 +188,8 @@ bool PrintBackendWin::EnumeratePrinters(PrinterList* printer_list) {
                nullptr, 0, &bytes_needed, &count_returned);
   if (!bytes_needed)
     return false;
-  std::unique_ptr<BYTE[]> printer_info_buffer(new BYTE[bytes_needed]);
+
+  auto printer_info_buffer = base::MakeUnique<BYTE[]>(bytes_needed);
   if (!EnumPrinters(PRINTER_ENUM_LOCAL | PRINTER_ENUM_CONNECTIONS, nullptr,
                     kLevel, printer_info_buffer.get(), bytes_needed,
                     &bytes_needed, &count_returned)) {
@@ -307,27 +309,29 @@ bool PrintBackendWin::GetPrinterSemanticCapsAndDefaults(
 bool PrintBackendWin::GetPrinterCapsAndDefaults(
     const std::string& printer_name,
     PrinterCapsAndDefaults* printer_info) {
+  DCHECK(printer_info);
+
   ScopedXPSInitializer xps_initializer;
-  if (!xps_initializer.initialized()) {
-    // TODO(sanjeevr): Handle legacy proxy case (with no prntvpt.dll)
-    return false;
-  }
-  if (!IsValidPrinter(printer_name)) {
+  CHECK(xps_initializer.initialized());
+
+  if (!IsValidPrinter(printer_name))
     return false;
-  }
-  DCHECK(printer_info);
-  HPTPROVIDER provider = NULL;
+
+  HPTPROVIDER provider = nullptr;
   std::wstring printer_name_wide = base::UTF8ToWide(printer_name);
   HRESULT hr = XPSModule::OpenProvider(printer_name_wide, 1, &provider);
-  if (provider) {
+  if (!provider)
+    return true;
+
+  {
     base::win::ScopedComPtr<IStream> print_capabilities_stream;
-    hr = CreateStreamOnHGlobal(NULL, TRUE,
+    hr = CreateStreamOnHGlobal(nullptr, TRUE,
                                print_capabilities_stream.GetAddressOf());
     DCHECK(SUCCEEDED(hr));
     if (print_capabilities_stream.Get()) {
       base::win::ScopedBstr error;
       hr = XPSModule::GetPrintCapabilities(
-          provider, NULL, print_capabilities_stream.Get(), error.Receive());
+          provider, nullptr, print_capabilities_stream.Get(), error.Receive());
       DCHECK(SUCCEEDED(hr));
       if (FAILED(hr)) {
         return false;
@@ -340,11 +344,11 @@ bool PrintBackendWin::GetPrinterCapsAndDefaults(
     ScopedPrinterHandle printer_handle;
     if (printer_handle.OpenPrinter(printer_name_wide.c_str())) {
       std::unique_ptr<DEVMODE, base::FreeDeleter> devmode_out(
-          CreateDevMode(printer_handle.Get(), NULL));
+          CreateDevMode(printer_handle.Get(), nullptr));
       if (!devmode_out)
         return false;
       base::win::ScopedComPtr<IStream> printer_defaults_stream;
-      hr = CreateStreamOnHGlobal(NULL, TRUE,
+      hr = CreateStreamOnHGlobal(nullptr, TRUE,
                                  printer_defaults_stream.GetAddressOf());
       DCHECK(SUCCEEDED(hr));
       if (printer_defaults_stream.Get()) {