Turn on -Wall -Wextra on Mac, and fix all the warnings that crop up for /usr/bin/g++ and Clang 3.3.

src/core/SkPicture.cpp

Index: src/core/SkPicture.cpp
diff --git a/src/core/SkPicture.cpp b/src/core/SkPicture.cpp
index 2b488dec02af69953e56124bb122f8831c7eeeb3..d8ad80dd67fd848a2ad7ddfea97e6321d77ea4ad 100644
--- a/src/core/SkPicture.cpp
+++ b/src/core/SkPicture.cpp
@@ -121,7 +121,7 @@ SkPicture::SkPicture() {
     fWidth = fHeight = 0;
 }
 
-SkPicture::SkPicture(const SkPicture& src) {
+SkPicture::SkPicture(const SkPicture& src) : INHERITED() {
     fWidth = src.fWidth;
     fHeight = src.fHeight;
     fRecord = NULL;