Don't attempt to use hardware video decoding if mf.dll doesn't exist.

media/gpu/dxva_video_decode_accelerator_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/gpu/dxva_video_decode_accelerator_win.h"
 
 #include <memory>
 
 #if !defined(OS_WIN)
 #error This file should only be built on Windows.
@@ skipping 137 matching lines @@
     0x9990, 0x9991, 0x9992, 0x9993, 0x9994, 0x9995, 0x9996, 0x9997, 0x9998,
     0x9999, 0x999a, 0x999b, 0x999c, 0x999d, 0x99a0, 0x99a2, 0x99a4,
 };
 
 // Legacy Intel GPUs (Second generation) which have trouble with resolutions
 // higher than 1920 x 1088
 static const DWORD g_IntelLegacyGPUList[] = {
     0x102, 0x106, 0x116, 0x126,
 };
 
+constexpr const wchar_t* const kMediaFoundationVideoDecoderDLLs[] = {

[sandersd (OOO until July 31), 2016/08/18 00:05:59]

This looks rather redundant. Does constexpr not imply any of the rest?

+    L"mf.dll", L"mfplat.dll", L"msmpeg2vdec.dll",
+};
+
 }  // namespace
 
 namespace media {
 
 static const VideoCodecProfile kSupportedProfiles[] = {
     H264PROFILE_BASELINE, H264PROFILE_MAIN,    H264PROFILE_HIGH,
     VP8PROFILE_ANY,       VP9PROFILE_PROFILE0, VP9PROFILE_PROFILE1,
     VP9PROFILE_PROFILE2,  VP9PROFILE_PROFILE3};
 
 CreateDXGIDeviceManager
@@ skipping 865 matching lines @@
 
 // static
 VideoDecodeAccelerator::SupportedProfiles
 DXVAVideoDecodeAccelerator::GetSupportedProfiles(
     const gpu::GpuPreferences& preferences) {
   TRACE_EVENT0("gpu,startup",
                "DXVAVideoDecodeAccelerator::GetSupportedProfiles");
 
   // TODO(henryhsu): Need to ensure the profiles are actually supported.
   SupportedProfiles profiles;
+
+  for (const wchar_t* mfdll : kMediaFoundationVideoDecoderDLLs) {
+    if (!::GetModuleHandle(mfdll)) {
+      // Windows N is missing the media foundation DLLs unless the media
+      // feature pack is installed.
+      DVLOG(ERROR) << mfdll << " is required for hardware video decoding";
+      return profiles;
+    }
+  }
   for (const auto& supported_profile : kSupportedProfiles) {
     if (!preferences.enable_accelerated_vpx_decode &&
         (supported_profile >= VP8PROFILE_MIN) &&
         (supported_profile <= VP9PROFILE_MAX)) {
       continue;
     }
     std::pair<int, int> min_resolution = GetMinResolution(supported_profile);
     std::pair<int, int> max_resolution = GetMaxResolution(supported_profile);
 
     SupportedProfile profile;
     profile.profile = supported_profile;
     profile.min_resolution.SetSize(min_resolution.first, min_resolution.second);
     profile.max_resolution.SetSize(max_resolution.first, max_resolution.second);
     profiles.push_back(profile);
   }
   return profiles;
 }
 
 // static
 void DXVAVideoDecodeAccelerator::PreSandboxInitialization() {
-  ::LoadLibrary(L"MFPlat.dll");
-  ::LoadLibrary(L"msmpeg2vdec.dll");
-  ::LoadLibrary(L"mf.dll");
+  for (const wchar_t* mfdll : kMediaFoundationVideoDecoderDLLs)
+    ::LoadLibrary(mfdll);
   ::LoadLibrary(L"dxva2.dll");
 
   if (base::win::GetVersion() > base::win::VERSION_WIN7) {
     LoadLibrary(L"msvproc.dll");
   } else {
 #if defined(ENABLE_DX11_FOR_WIN7)
     LoadLibrary(L"mshtmlmedia.dll");
 #endif
   }
 }
@@ skipping 1552 matching lines @@
   SetState(kConfigChange);
   Invalidate();
   Initialize(config_, client_);
   decoder_thread_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&DXVAVideoDecodeAccelerator::DecodePendingInputBuffers,
                  base::Unretained(this)));
 }
 
 }  // namespace media