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

remoting/host/host_attributes.cc

Index: remoting/host/host_attributes.cc
diff --git a/remoting/host/host_attributes.cc b/remoting/host/host_attributes.cc
index 307d04e289fd66c4df9a4ed1219155dcf2904287..6f929867c2c6747aab5d04b1eb111741634092fd 100644
--- a/remoting/host/host_attributes.cc
+++ b/remoting/host/host_attributes.cc
@@ -67,7 +67,7 @@ inline constexpr bool IsNonOfficialBuild() {
 #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;
@@ -75,7 +75,7 @@ inline bool MinD3DFeatureLevelGreatThan10() {
 
 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;
@@ -83,7 +83,7 @@ inline bool MinD3DFeatureLevelGreatThan11() {
 
 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;
@@ -119,6 +119,11 @@ static constexpr Attribute kAttributes[] = {
 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]':
@@ -133,6 +138,10 @@ std::string GetHostAttributes() {
       result.append(attribute.name);
     }
   }
+#if defined(OS_WIN)
+  // Avoid the warning of unused variable.
+  controller = nullptr;
+#endif
 
   return result;
 }