Added support for EXT_frag_depth

gpu/command_buffer/service/feature_info.cc

Index: gpu/command_buffer/service/feature_info.cc
diff --git a/gpu/command_buffer/service/feature_info.cc b/gpu/command_buffer/service/feature_info.cc
index fa8abdd2619600175e20b965a7dc5a79e7f16e5e..474946b65f1b887bf19cb44cbb056e3633432a0a 100644
--- a/gpu/command_buffer/service/feature_info.cc
+++ b/gpu/command_buffer/service/feature_info.cc
@@ -115,7 +115,8 @@ FeatureInfo::FeatureFlags::FeatureFlags()
       native_vertex_array_object(false),
       enable_shader_name_hashing(false),
       enable_samplers(false),
-      ext_draw_buffers(false) {
+      ext_draw_buffers(false),
+      ext_frag_depth(false) {
 }
 
 FeatureInfo::Workarounds::Workarounds() :
@@ -695,6 +696,11 @@ void FeatureInfo::AddFeatures(const CommandLine& command_line) {
     }
   }
 
+  if (extensions.Contains("GL_EXT_frag_depth") || gfx::HasDesktopGLFeatures()) {
+    AddExtensionString("GL_EXT_frag_depth");
+    feature_flags_.ext_frag_depth = true;
+  }
+
   if (!disallowed_features_.swap_buffer_complete_callback)
     AddExtensionString("GL_CHROMIUM_swapbuffers_complete_callback");