Switch out random number generator for tests, benches, samples.

This change makes tests, benches and samples use the new SkMWCRandom PRNG. GMs will be saved for another time, as they'll require rebaselining.

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

Author: jvanverth@google.com

Review URL: https://chromiumcodereview.appspot.com/23653018

git-svn-id: http://skia.googlecode.com/svn/trunk@11136 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/samplecode/SampleClip.cpp b/samplecode/SampleClip.cpp
index 3a38724..a35f42c 100644
--- a/samplecode/SampleClip.cpp
+++ b/samplecode/SampleClip.cpp
@@ -17,7 +17,7 @@
 #define H   200
 
 static void show_text(SkCanvas* canvas, bool doAA) {
-    SkRandom rand;
+    SkMWCRandom rand;
     SkPaint paint;
     paint.setAntiAlias(doAA);
     paint.setLCDRenderText(true);
@@ -32,7 +32,7 @@
 }
 
 static void show_fill(SkCanvas* canvas, bool doAA) {
-    SkRandom rand;
+    SkMWCRandom rand;
     SkPaint paint;
     paint.setAntiAlias(doAA);
 
@@ -53,13 +53,13 @@
     }
 }
 
-static SkScalar randRange(SkRandom& rand, SkScalar min, SkScalar max) {
+static SkScalar randRange(SkMWCRandom& rand, SkScalar min, SkScalar max) {
     SkASSERT(min <= max);
     return min + SkScalarMul(rand.nextUScalar1(), max - min);
 }
 
 static void show_stroke(SkCanvas* canvas, bool doAA, SkScalar strokeWidth, int n) {
-    SkRandom rand;
+    SkMWCRandom rand;
     SkPaint paint;
     paint.setAntiAlias(doAA);
     paint.setStyle(SkPaint::kStroke_Style);