Add query for block dimensions of a given format

src/opts/SkTextureCompression_opts_arm.cpp

Index: src/opts/SkTextureCompression_opts_arm.cpp
diff --git a/src/opts/SkTextureCompression_opts_arm.cpp b/src/opts/SkTextureCompression_opts_arm.cpp
index 3a97a5ed9a161a099f60324c1d6ca86f1b6f49d7..36ff15c1d11157cfcf69e7d548c008225f068367 100644
--- a/src/opts/SkTextureCompression_opts_arm.cpp
+++ b/src/opts/SkTextureCompression_opts_arm.cpp
@@ -36,3 +36,24 @@ SkTextureCompressorGetPlatformProc(SkColorType colorType, SkTextureCompressor::F
     }
 #endif
 }
+
+bool SkTextureCompressorGetPlatformDims(SkTextureCompressor::Format fmt, int* dimX, int* dimY) {
+#if SK_ARM_NEON_IS_NONE
+    return false;
+#else
+#if SK_ARM_NEON_IS_DYNAMIC
+    if (!sk_cpu_arm_has_neon()) {
+        return false;
+    }
+#endif
+    switch (fmt) {
+        case SkTextureCompressor::kR11_EAC_Format:
+            *dimX = 16;
+            *dimY = 4;
+            return true;
+        default:
+            return false;
+    }
+    return false;
+#endif
+}