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

src/utils/SkLayer.cpp

Index: src/utils/SkLayer.cpp
diff --git a/src/utils/SkLayer.cpp b/src/utils/SkLayer.cpp
index a96d9214572fbcb5661a097a7289261a4e066d88..126dd92198d7e44908be7db19302f2fd348f748e 100644
--- a/src/utils/SkLayer.cpp
+++ b/src/utils/SkLayer.cpp
@@ -36,7 +36,7 @@ SkLayer::SkLayer() {
 #endif
 }
 
-SkLayer::SkLayer(const SkLayer& src) {
+SkLayer::SkLayer(const SkLayer& src) : INHERITED() {
     fParent = NULL;
     m_opacity = src.m_opacity;
     m_size = src.m_size;