Create base class for common functionality of Web{Local,Remote}Frame

third_party/WebKit/Source/web/FrameLoaderClientImpl.cpp

Index: third_party/WebKit/Source/web/FrameLoaderClientImpl.cpp
diff --git a/third_party/WebKit/Source/web/FrameLoaderClientImpl.cpp b/third_party/WebKit/Source/web/FrameLoaderClientImpl.cpp
index 7f43290a4dd296830ef59a298d841897d73f9a5d..1c1abfeafa230b5cf10b18b28150325d5e269c27 100644
--- a/third_party/WebKit/Source/web/FrameLoaderClientImpl.cpp
+++ b/third_party/WebKit/Source/web/FrameLoaderClientImpl.cpp
@@ -108,6 +108,21 @@
 
 namespace blink {
 
+namespace {
+
+// Convenience helper for frame tree helpers in FrameClient to reduce the amount
+// of null-checking boilerplate code. Since the frame tree is maintained in the
+// web/ layer, the frame tree helpers often have to deal with null WebFrames:
+// for example, a frame with no parent will return null for WebFrame::parent().
+// TODO(dcheng): Remove duplication between FrameLoaderClientImpl and
+// RemoteFrameClientImpl somehow...
+Frame* toCoreFrame(WebFrame* frame)
+{
+    return frame ? frame->toImplBase()->frame() : nullptr;
+}
+
+} // namespace
+
 FrameLoaderClientImpl::FrameLoaderClientImpl(WebLocalFrameImpl* frame)
     : m_webFrame(frame)
 {