More code cleanup in print_backend_win.cc

- Make sure ScopedProvider cannot be copied.
- Remove out-parameter from GetDeviceCapabilityArray().
- Use base::HeapArray instead of calling std::make_unique<T[]>().

Change-Id: I9dade099778c0d90dda9b35319fdc0652c87ecb7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5840730
Reviewed-by: Alan Screen <awscreen@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1352305}

printing/backend/print_backend_win.cc

@@ -16,7 +16,9 @@
 
 #include <memory>
 #include <utility>
+#include <vector>
 
+#include "base/containers/heap_array.h"
 #include "base/logging.h"
 #include "base/memory/free_deleter.h"
 #include "base/numerics/safe_conversions.h"
@@ -47,6 +49,8 @@ namespace {
 class ScopedProvider {
  public:
   explicit ScopedProvider(HPTPROVIDER provider) : provider_(provider) {}
+  ScopedProvider(const ScopedProvider&) = delete;
+  ScopedProvider& operator=(const ScopedProvider&) = delete;
 
   // Once the object is destroyed, it automatically closes the provider by
   // calling the XPSModule API.
@@ -94,24 +98,25 @@ HRESULT StreamOnHGlobalToString(IStream* stream, std::string* out) {
 }
 
 template <class T>
-void GetDeviceCapabilityArray(const wchar_t* printer,
-                              const wchar_t* port,
-                              WORD id,
-                              std::vector<T>* result) {
+std::vector<T> GetDeviceCapabilityArray(const wchar_t* printer,
+                                        const wchar_t* port,
+                                        WORD id) {
   int count = DeviceCapabilities(printer, port, id, nullptr, nullptr);
-  if (count <= 0)
-    return;
+  if (count <= 0) {
+    return {};
+  }
 
-  std::vector<T> tmp;
-  tmp.resize(count * 2);
+  std::vector<T> results;
+  results.resize(count * 2);
   count = DeviceCapabilities(printer, port, id,
-                             reinterpret_cast<LPTSTR>(tmp.data()), nullptr);
-  if (count <= 0)
-    return;
+                             reinterpret_cast<LPTSTR>(results.data()), nullptr);
+  if (count <= 0) {
+    return {};
+  }
 
-  CHECK_LE(static_cast<size_t>(count), tmp.size());
-  tmp.resize(count);
-  result->swap(tmp);
+  CHECK_LE(static_cast<size_t>(count), results.size());
+  results.resize(count);
+  return results;
 }
 
 gfx::Size GetDefaultDpi(HDC hdc) {
@@ -161,14 +166,12 @@ bool LoadPaper(const wchar_t* printer,
   DCHECK_EQ(sizeof(PaperName), sizeof(wchar_t) * kMaxPaperName);
 
   // Paper
-  std::vector<PaperName> names;
-  GetDeviceCapabilityArray(printer, port, DC_PAPERNAMES, &names);
-
-  std::vector<POINT> sizes;
-  GetDeviceCapabilityArray(printer, port, DC_PAPERSIZE, &sizes);
-
-  std::vector<WORD> ids;
-  GetDeviceCapabilityArray(printer, port, DC_PAPERS, &ids);
+  std::vector<PaperName> names =
+      GetDeviceCapabilityArray<PaperName>(printer, port, DC_PAPERNAMES);
+  std::vector<POINT> sizes =
+      GetDeviceCapabilityArray<POINT>(printer, port, DC_PAPERSIZE);
+  std::vector<WORD> ids =
+      GetDeviceCapabilityArray<WORD>(printer, port, DC_PAPERS);
 
   DCHECK_EQ(ids.size(), sizes.size());
   DCHECK_EQ(names.size(), sizes.size());
@@ -271,9 +274,8 @@ void LoadDpi(const wchar_t* printer,
              const wchar_t* port,
              const DEVMODE* devmode,
              PrinterSemanticCapsAndDefaults* caps) {
-  std::vector<POINT> dpis;
-  GetDeviceCapabilityArray(printer, port, DC_ENUMRESOLUTIONS, &dpis);
-
+  std::vector<POINT> dpis =
+      GetDeviceCapabilityArray<POINT>(printer, port, DC_ENUMRESOLUTIONS);
   for (size_t i = 0; i < dpis.size(); ++i)
     caps->dpis.push_back(gfx::Size(dpis[i].x, dpis[i].y));
 
@@ -342,9 +344,10 @@ mojom::ResultCode PrintBackendWin::EnumeratePrinters(
     return GetResultCodeFromSystemErrorCode(code);
   }
 
-  auto printer_info_buffer = std::make_unique<BYTE[]>(bytes_needed);
-  if (!EnumPrinters(kFlags, nullptr, kLevel, printer_info_buffer.get(),
-                    bytes_needed, &bytes_needed, &count_returned)) {
+  auto printer_info_buffer = base::HeapArray<BYTE>::Uninit(bytes_needed);
+  if (!EnumPrinters(kFlags, nullptr, kLevel, printer_info_buffer.data(),
+                    printer_info_buffer.size(), &bytes_needed,
+                    &count_returned)) {
     NOTREACHED_IN_MIGRATION();
     return GetResultCodeFromSystemErrorCode(logging::GetLastSystemErrorCode());
   }
@@ -354,8 +357,8 @@ mojom::ResultCode PrintBackendWin::EnumeratePrinters(
   std::string default_printer;
   GetDefaultPrinterName(default_printer);
 
-  PRINTER_INFO_4* printer_info =
-      reinterpret_cast<PRINTER_INFO_4*>(printer_info_buffer.get());
+  const auto* printer_info =
+      reinterpret_cast<PRINTER_INFO_4*>(printer_info_buffer.data());
   for (DWORD index = 0; index < count_returned; index++) {
     ScopedPrinterHandle printer;
     if (!printer.OpenPrinterWithName(printer_info[index].pPrinterName)) {