Add PLOG to PreSandboxInitialization

Add logs to the pre-sandbox dll loading calls, to see if this is the
original source of the error.

Bug: 1055602
Change-Id: I022036006a92dd5f454e6336127b9f19be163c9b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2071908
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#744714}

media/gpu/windows/dxva_video_decode_accelerator_win.cc

@@ -1321,15 +1321,22 @@ DXVAVideoDecodeAccelerator::GetSupportedProfiles(
 
 // static
 void DXVAVideoDecodeAccelerator::PreSandboxInitialization() {
-  for (const wchar_t* mfdll : kMediaFoundationVideoDecoderDLLs)
-    ::LoadLibrary(mfdll);
-  ::LoadLibrary(L"dxva2.dll");
+  for (const wchar_t* mfdll : kMediaFoundationVideoDecoderDLLs) {
+    if (!::LoadLibrary(mfdll))
+      PLOG(ERROR) << "DXVAVDA fatal error: could not LoadLibrary: " << mfdll;
+  }
+
+  if (!::LoadLibrary(L"dxva2.dll"))
+    PLOG(ERROR) << "DXVAVDA fatal error: could not LoadLibrary: dxva2.dll";
 
   if (base::win::GetVersion() >= base::win::Version::WIN8) {
-    LoadLibrary(L"msvproc.dll");
+    if (!LoadLibrary(L"msvproc.dll"))
+      PLOG(ERROR) << "DXVAVDA fatal error: could not LoadLibrary: msvproc.dll";
   } else {
 #if defined(ENABLE_DX11_FOR_WIN7)
-    LoadLibrary(L"mshtmlmedia.dll");
+    if (!LoadLibrary(L"mshtmlmedia.dll"))
+      PLOG(ERROR)
+          << "DXVAVDA fatal error: could not LoadLibrary: mshtmlmedia.dll";
 #endif
   }
 }