add code-style for slides

BUG=skia:
TBR=

Review URL: https://codereview.chromium.org/697923002
diff --git a/resources/slides_content.lua b/resources/slides_content.lua
index a2f376a..9b20e43 100644
--- a/resources/slides_content.lua
+++ b/resources/slides_content.lua
@@ -21,6 +21,7 @@
 
 <transition= rotate>
 
+<blockstyle = code>
 Optimize for CPU variety
 - x86 - 32bit (SSE, SSE2, ...), 64bit
 - Arm - thumb, arm, NEON, ... 64bit?