[Chromoting] Use latest API to check whether DX capturer is supported

remoting/host/host_attributes.cc

 // Copyright 2016 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 "remoting/host/host_attributes.h"
 
 #if defined(OS_WIN)
 #include <D3DCommon.h>
 #endif
 
@@ skipping 49 matching lines @@
 #endif
 }
 
 inline constexpr bool IsNonOfficialBuild() {
   return !IsOfficialBuild();
 }
 
 #if defined(OS_WIN)
 inline bool MinD3DFeatureLevelGreatThan10() {
   webrtc::DxgiDuplicatorController::D3dInfo info;
-  if (webrtc::DxgiDuplicatorController::Instance()->RetrieveD3dInfo(&info)) {
+  if (webrtc::ScreenCapturerWinDirectx::RetrieveD3dInfo(&info)) {

[Sergey Ulanov, 2017/06/26 23:55:23]

Where is the change that made RetrieveD3dInfo() static? I think it would be
better to keep it non-static.

[Hzj_jie, 2017/06/27 04:37:28]

No, it's always static
(https://cs.chromium.org/chromium/src/third_party/webrtc/modules/desktop_captu...),
but I used a wrong function before. IMO, if possible, using
DxgiDuplicatorController should be avoided.

     return info.min_feature_level >= D3D_FEATURE_LEVEL_10_0;
   }
   return false;
 }
 
 inline bool MinD3DFeatureLevelGreatThan11() {
   webrtc::DxgiDuplicatorController::D3dInfo info;
-  if (webrtc::DxgiDuplicatorController::Instance()->RetrieveD3dInfo(&info)) {
+  if (webrtc::ScreenCapturerWinDirectx::RetrieveD3dInfo(&info)) {
     return info.min_feature_level >= D3D_FEATURE_LEVEL_11_0;
   }
   return false;
 }
 
 inline bool MinD3DFeatureLevelGreatThan12() {
   webrtc::DxgiDuplicatorController::D3dInfo info;
-  if (webrtc::DxgiDuplicatorController::Instance()->RetrieveD3dInfo(&info)) {
+  if (webrtc::ScreenCapturerWinDirectx::RetrieveD3dInfo(&info)) {
     return info.min_feature_level >= D3D_FEATURE_LEVEL_12_0;
   }
   return false;
 }
 #endif
 
 // By using arraysize() macro in base/macros.h, it's illegal to have empty
 // arrays.
 //
 // error: no matching function for call to 'ArraySizeHelper'
@@ skipping 15 matching lines @@
   { "MinD3DGT11", &MinD3DFeatureLevelGreatThan11 },
   { "MinD3DGT12", &MinD3DFeatureLevelGreatThan12 },
 #endif
 };
 
 }  // namespace
 
 static_assert(std::is_pod<Attribute>::value, "Attribute should be POD.");
 
 std::string GetHostAttributes() {
+#if defined(OS_WIN)
+  // Ensure the following ScreenCapturerWinDirectx contructions won't
+  // initialize and unload DxgiDuplicatorController.

[Sergey Ulanov, 2017/06/26 23:55:23]

This doesn't look like the best solution. GetHostAttributes() is the only place
where kAttributes is used. There must be a cleaner and more readable solution.
E.g. you could add the following in the end of this function

 if (webrtc::ScreenCapturerWinDirectx::RetrieveD3dInfo(&info)) {
   switch (info.min_feature_level) {
    /// call result.append() for appropriate features depending 
    /// on the version.
   }
 }

And then remove all MinD3DFeatureLevelGreatThan*()

[Hzj_jie, 2017/06/27 04:37:28]

Done.

+  auto controller = webrtc::DxgiDuplicatorController::Instance();
+#endif
   std::string result;
   // By using ranged for-loop, MSVC throws error C3316:
   // 'const remoting::StaticAttribute [0]':
   // an array of unknown size cannot be used in a range-based for statement.
   for (size_t i = 0; i < arraysize(kAttributes); i++) {
     const auto& attribute = kAttributes[i];
     DCHECK_EQ(std::string(attribute.name).find(kSeparator), std::string::npos);
     if (attribute.get_value_func()) {
       if (!result.empty()) {
         result.append(kSeparator);
       }
       result.append(attribute.name);
     }
   }
+#if defined(OS_WIN)
+  // Avoid the warning of unused variable.
+  controller = nullptr;
+#endif
 
   return result;
 }
 
 }  // namespace remoting