Added toString to SkDrawLooper-derived classes

This gives a little more visibility into the blurred rect case in the debugger. Unfortunately the lack of an SkPaint::toString limits how much is shown. SkPaint::toString is blocked on the visibility of SkFontDescriptor (it is in ports).

[DerekS, 2013-01-25 14:11:26]

https://codereview.appspot.com/7195054/diff/1/src/effects/SkBlurDrawLooper.cpp
File src/effects/SkBlurDrawLooper.cpp (right):

https://codereview.appspot.com/7195054/diff/1/src/effects/SkBlurDrawLooper.cp...
src/effects/SkBlurDrawLooper.cpp:134: str->append("dx: ");
why not use str->appendf(...) to reduce the number of appends needed.

https://codereview.appspot.com/7195054/diff/1/src/effects/SkLayerDrawLooper.cpp
File src/effects/SkLayerDrawLooper.cpp (right):

https://codereview.appspot.com/7195054/diff/1/src/effects/SkLayerDrawLooper.c...
src/effects/SkLayerDrawLooper.cpp:251: static void add_flag_to_string(SkString*
string, bool flag, const char* flagStr, bool* needSeparator) {
is there a common file we can put this in so we don't need to redefine it
everywhere?

[robertphillips, 2013-01-28 20:14:40]

PTAL

https://codereview.appspot.com/7195054/diff/1/src/effects/SkBlurDrawLooper.cpp
File src/effects/SkBlurDrawLooper.cpp (right):

https://codereview.appspot.com/7195054/diff/1/src/effects/SkBlurDrawLooper.cp...
src/effects/SkBlurDrawLooper.cpp:134: str->append("dx: ");
I thought using appendScalar was preferred due to its changeable nature?

[DerekS, 2013-01-28 20:20:50]

lgtm

[robertphillips, 2013-01-28 20:22:22]

committed as r7422