Use asNewCustomStage instead of asABitmap in SkGpuDevice, also removed now-unecessary twoPointRadialParams parameter from asABitmap.

In SkGpuDevice we still fall back on using asABitmap for effects that don't have asNewCustomStage implemented, but it still simplifies things a fair amount.
Review URL: https://codereview.appspot.com/6430060

git-svn-id: http://skia.googlecode.com/svn/trunk@4755 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/core/SkShader.cpp b/src/core/SkShader.cpp
index a0ae49d..cf522b6 100644
--- a/src/core/SkShader.cpp
+++ b/src/core/SkShader.cpp
@@ -192,7 +192,7 @@
 //////////////////////////////////////////////////////////////////////////////
 
 SkShader::BitmapType SkShader::asABitmap(SkBitmap*, SkMatrix*,
-                                         TileMode*, SkScalar*) const {
+                                         TileMode*) const {
     return kNone_BitmapType;
 }
 
@@ -316,8 +316,7 @@
 
 // if we had a asAColor method, that would be more efficient...
 SkShader::BitmapType SkColorShader::asABitmap(SkBitmap* bitmap, SkMatrix* matrix,
-                                              TileMode modes[],
-                                      SkScalar* twoPointRadialParams) const {
+                                              TileMode modes[]) const {
     return kNone_BitmapType;
 }