Add new Query class for debugging

This class can be used to perform occlusion queries. An occlusion query
can be used to test whether an object is entirely hidden or not.

Change-Id: Ida456df81dbe008a64d3ff4cb7879340785c6abf
diff --git a/libs/hwui/Extensions.h b/libs/hwui/Extensions.h
index 3112244..5e574a6 100644
--- a/libs/hwui/Extensions.h
+++ b/libs/hwui/Extensions.h
@@ -42,6 +42,10 @@
     inline bool has4BitStencil() const { return mHas4BitStencil; }
     inline bool hasNvSystemTime() const { return mHasNvSystemTime; }
 
+    inline bool hasPixelBufferObjects() const { return mVersionMajor >= 3; }
+    inline bool hasOcclusionQueries() const { return mVersionMajor >= 3; }
+    inline bool hasFloatTextures() const { return mVersionMajor >= 3; }
+
     inline int getMajorGlVersion() const { return mVersionMajor; }
     inline int getMinorGlVersion() const { return mVersionMinor; }