add helpers to initialize our var-int args before calling GL. Some drivers
assert that those are zero on input, even though they are logically
output-only parameters.



git-svn-id: http://skia.googlecode.com/svn/trunk@688 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gpu/src/GrGpuGL.h b/gpu/src/GrGpuGL.h
index 7701df9..dc766be 100644
--- a/gpu/src/GrGpuGL.h
+++ b/gpu/src/GrGpuGL.h
@@ -180,6 +180,16 @@
     #define SK_GL_HAS_COLOR4UB
 #endif
 
+/*
+ *  Some drivers want the var-int arg to be zero-initialized on input.
+ */
+#define GR_GL_INIT_ZERO     0
+#define GR_GL_GetIntegerv(e, p)     \
+    do {                            \
+        *(p) = GR_GL_INIT_ZERO;     \
+        GR_GL(GetIntegerv(e, p));   \
+    } while (0)
+
 #endif