Add support for all compressed formats in KTX file format

R=robertphillips@google.com

Author: krajcevski@google.com

Review URL: https://codereview.chromium.org/440783004
diff --git a/src/gpu/SkGr.cpp b/src/gpu/SkGr.cpp
index 5c0464d..0a45100 100644
--- a/src/gpu/SkGr.cpp
+++ b/src/gpu/SkGr.cpp
@@ -11,6 +11,7 @@
 #include "SkData.h"
 #include "SkMessageBus.h"
 #include "SkPixelRef.h"
+#include "SkTextureCompressor.h"
 #include "GrResourceCache.h"
 #include "GrGpu.h"
 #include "effects/GrDitherEffect.h"
@@ -165,7 +166,7 @@
         SkKTXFile ktx(data);
 
         // Is it actually an ETC1 texture?
-        if (!ktx.isETC1()) {
+        if (!ktx.isCompressedFormat(SkTextureCompressor::kETC1_Format)) {
             return NULL;
         }