Revert "Revert "fix [2793164] Spam 2x/second with TOT master in SurfaceFlinger""

This reverts commit 330dd304a471d260a73e342a240921c03c825f99.
diff --git a/libs/surfaceflinger/LayerBlur.cpp b/libs/surfaceflinger/LayerBlur.cpp
index c1c440b..64a43c7 100644
--- a/libs/surfaceflinger/LayerBlur.cpp
+++ b/libs/surfaceflinger/LayerBlur.cpp
@@ -147,7 +147,9 @@
     Region::const_iterator const end = clip.end();
     if (it != end) {
 #if defined(GL_OES_texture_external)
-        glDisable(GL_TEXTURE_EXTERNAL_OES);
+        if (GLExtensions::getInstance().haveTextureExternal()) {
+            glDisable(GL_TEXTURE_EXTERNAL_OES);
+        }
 #endif
         glEnable(GL_TEXTURE_2D);
         glBindTexture(GL_TEXTURE_2D, mTextureName);
@@ -181,7 +183,7 @@
             bl.data = (GGLubyte*)pixels;            
             blurFilter(&bl, 8, 2);
 
-            if (mFlags & (DisplayHardware::NPOT_EXTENSION)) {
+            if (GLExtensions::getInstance().haveNpot()) {
                 glTexImage2D(GL_TEXTURE_2D, 0, mReadFormat, w, h, 0,
                         mReadFormat, mReadType, pixels);
                 mWidthScale  = 1.0f / w;