[chromium] Remove unused WebLayerTreeViewClient calls https://bugs.webkit.org/show_bug.cgi?id=110923 Reviewed by Adrienne Walker. These notifications existed for instrumentation, but now the instrumentation routes through WebDevToolsAgent. Source/Platform: * chromium/public/WebLayerTreeViewClient.h: Source/WebKit/chromium: * src/WebViewImpl.cpp: * src/WebViewImpl.h: * tests/WebLayerTreeViewTestCommon.h: git-svn-id: https://svn.webkit.org/repository/webkit/trunk/Source/Platform/chromium/public@144120 268f45cc-cd09-0410-ab3c-d52691b4dbfc