make onReadPixels protected and have default impl (so we can remove chrome override)

src/core/SkDevice.cpp

Index: src/core/SkDevice.cpp
diff --git a/src/core/SkDevice.cpp b/src/core/SkDevice.cpp
index b9c923cf5804e53ebdd022bf8d66ba4ee4af2b1a..666e456e8cb539d093c534ed77f95fdb7d1c21c7 100644
--- a/src/core/SkDevice.cpp
+++ b/src/core/SkDevice.cpp
@@ -190,6 +190,10 @@ bool SkBaseDevice::onWritePixels(const SkImageInfo&, const void*, size_t, int, i
     return false;
 }
 
+bool SkBaseDevice::onReadPixels(const SkBitmap&, int x, int y, SkCanvas::Config8888) {
+    return false;
+}
+
 #ifdef SK_SUPPORT_LEGACY_WRITEPIXELSCONFIG
 void SkBaseDevice::writePixels(const SkBitmap&, int x, int y, SkCanvas::Config8888) {}
 #endif