More GPU blur fixes.

- clamp the max. radius to 128, as the software path does
- use a more accurate radius-to-sigma conversion (0.6 instead of 0.6666)
- make SampleBlur derive from SampleView, not SkView, so benchmark mode ('f')
works
- implement a new BigBlur sample to test large radii

Review URL:  http://codereview.appspot.com/4726043



git-svn-id: http://skia.googlecode.com/svn/trunk@1871 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/samplecode/SampleBlur.cpp b/samplecode/SampleBlur.cpp
index d2ea2b0..98cfcfb 100644
--- a/samplecode/SampleBlur.cpp
+++ b/samplecode/SampleBlur.cpp
@@ -41,7 +41,7 @@
     return bm;
 }
 
-class BlurView : public SkView {
+class BlurView : public SampleView {
     SkBitmap    fBM;
 public:
 	BlurView() {
@@ -61,7 +61,7 @@
         canvas->drawColor(0xFFDDDDDD);
     }
 
-    virtual void onDraw(SkCanvas* canvas) {
+    virtual void onDrawContent(SkCanvas* canvas) {
         drawBG(canvas);
 
         SkBlurMaskFilter::BlurStyle NONE = SkBlurMaskFilter::BlurStyle(-999);