Change old PRG to be SkLCGRandom; change new one to SkRandom

The goal here is to get people to start using the new random number
generator, while leaving the old one in place so we don't have to 
rebaseline GMs.

R=reed@google.com, bsalomon@google.com

Author: jvanverth@google.com

Review URL: https://chromiumcodereview.appspot.com/23576015

git-svn-id: http://skia.googlecode.com/svn/trunk@11169 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gm/convexpaths.cpp b/gm/convexpaths.cpp
index 668e01c..b1b2696 100644
--- a/gm/convexpaths.cpp
+++ b/gm/convexpaths.cpp
@@ -261,7 +261,7 @@
 
     SkPaint paint;
     paint.setAntiAlias(true);
-    SkRandom rand;
+    SkLCGRandom rand;
     canvas->translate(20 * SK_Scalar1, 20 * SK_Scalar1);
 
     // As we've added more paths this has gotten pretty big. Scale the whole thing down.