Warn unused result for ScopedHString::ResolveCoreWinRTStringDelayload()

Also fix MediaFoundationProtectionManager to check the result of
ScopedHString::ResolveCoreWinRTStringDelayload().

Change-Id: Ic9e37cfe3a7a53fd38332002d2396345ea1f78cf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2119373
Commit-Queue: Xiaohan Wang <xhwang@chromium.org>
Reviewed-by: Robert Liao <robliao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#753238}

base/win/scoped_hstring.h

@@ -7,6 +7,7 @@
 
 #include <hstring.h>
 
+#include "base/compiler_specific.h"
 #include "base/scoped_generic.h"
 #include "base/strings/string_piece_forward.h"
 
@@ -61,7 +62,7 @@ class BASE_EXPORT ScopedHString
   static ScopedHString Create(StringPiece str);
 
   // Loads all required HSTRING functions, available from Win8 and onwards.
-  static bool ResolveCoreWinRTStringDelayload();
+  static bool ResolveCoreWinRTStringDelayload() WARN_UNUSED_RESULT;
 
   // Returns a view into the memory buffer managed by the instance. The returned
   // StringPiece is only valid during the lifetime of this ScopedHString

media/renderers/win/media_foundation_protection_manager.cc

@@ -24,9 +24,11 @@ MediaFoundationProtectionManager::~MediaFoundationProtectionManager() = default;
 HRESULT MediaFoundationProtectionManager::RuntimeClassInitialize() {
   DVLOG(1) << __func__ << ": this=" << this;
 
+  if (!base::win::ScopedHString::ResolveCoreWinRTStringDelayload())
+    return E_FAIL;
+
   // Init an empty |property_set_| as MFMediaEngine could access it via
   // |get_Properties| before we populate it within SetPMPServer.
-  base::win::ScopedHString::ResolveCoreWinRTStringDelayload();
   base::win::ScopedHString property_set_id = base::win::ScopedHString::Create(
       RuntimeClass_Windows_Foundation_Collections_PropertySet);
   RETURN_IF_FAILED(
@@ -53,11 +55,11 @@ HRESULT MediaFoundationProtectionManager::SetPMPServer(
   ComPtr<ABI::Windows::Foundation::Collections::IMap<HSTRING, IInspectable*>>
       property_map;
   RETURN_IF_FAILED(property_set_.As(&property_map));
-  boolean replaced = false;
-  base::win::ScopedHString::ResolveCoreWinRTStringDelayload();
+
   // MFMediaEngine uses |pmp_server_key| to get the Protected Media Path (PMP)
   // server used for playing protected content. This is not currently documented
   // in MSDN.
+  boolean replaced = false;
   base::win::ScopedHString pmp_server_key = base::win::ScopedHString::Create(
       L"Windows.Media.Protection.MediaProtectionPMPServer");
   RETURN_IF_FAILED(