Add call sites for OpenGL's debug label extension

Change-Id: I9c689127e8166cbef92c935f8aa07217ab806dda
diff --git a/libs/hwui/Caches.h b/libs/hwui/Caches.h
index 65ff9ad..58361c9 100644
--- a/libs/hwui/Caches.h
+++ b/libs/hwui/Caches.h
@@ -107,7 +107,7 @@
     };
 
     /**
-     * Initializes the cache.
+     * Initialize caches.
      */
     void init();
 
@@ -247,15 +247,30 @@
     GammaFontRenderer fontRenderer;
     ResourceCache resourceCache;
 
+    // Debug methods
     PFNGLINSERTEVENTMARKEREXTPROC eventMark;
     PFNGLPUSHGROUPMARKEREXTPROC startMark;
     PFNGLPOPGROUPMARKEREXTPROC endMark;
 
+    PFNGLLABELOBJECTEXTPROC setLabel;
+    PFNGLGETOBJECTLABELEXTPROC getLabel;
+
 private:
-    static void eventMarkNull(GLsizei length, const GLchar *marker) { }
-    static void startMarkNull(GLsizei length, const GLchar *marker) { }
+    void initExtensions();
+    void initConstraints();
+
+    static void eventMarkNull(GLsizei length, const GLchar* marker) { }
+    static void startMarkNull(GLsizei length, const GLchar* marker) { }
     static void endMarkNull() { }
 
+    static void setLabelNull(GLenum type, uint object, GLsizei length,
+            const char* label) { }
+    static void getLabelNull(GLenum type, uint object, GLsizei bufferSize,
+            GLsizei* length, char* label) {
+        if (length) *length = 0;
+        if (label) *label = '\0';
+    }
+
     GLuint mCurrentBuffer;
     GLuint mCurrentIndicesBuffer;
     void* mCurrentPositionPointer;