Import glTextureBarrier

BUG=skia:

Review URL: https://codereview.chromium.org/1090163002
diff --git a/src/gpu/GrDrawTargetCaps.h b/src/gpu/GrDrawTargetCaps.h
index 08f4f43..e1fd1cf 100644
--- a/src/gpu/GrDrawTargetCaps.h
+++ b/src/gpu/GrDrawTargetCaps.h
@@ -86,6 +86,7 @@
 #endif
     bool compressedTexSubImageSupport() const { return fCompressedTexSubImageSupport; }
     bool oversizedStencilSupport() const { return fOversizedStencilSupport; }
+    bool textureBarrierSupport() const { return fTextureBarrierSupport; }
 
     bool useDrawInsteadOfClear() const { return fUseDrawInsteadOfClear; }
 
@@ -157,6 +158,7 @@
     bool fGpuTracingSupport             : 1;
     bool fCompressedTexSubImageSupport  : 1;
     bool fOversizedStencilSupport       : 1;
+    bool fTextureBarrierSupport         : 1;
     // Driver workaround
     bool fUseDrawInsteadOfClear         : 1;