Avoid element id collisions with the visual viewport

third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp

Index: third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp b/third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp
index 18d7bc3970f992c42e2468c61fbd5260de52b425..59b67731d48d7a9578daa5c425a2eb435169fe7d 100644
--- a/third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp
+++ b/third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp
@@ -1155,6 +1155,12 @@ void GraphicsLayer::setElementId(const CompositorElementId& id) {
     layer->setElementId(id);
 }
 
+CompositorElementId GraphicsLayer::elementId() const {
+  if (WebLayer* layer = platformLayer())
+    return layer->elementId();
+  return CompositorElementId();
+}
+
 void GraphicsLayer::setCompositorMutableProperties(uint32_t properties) {
   if (WebLayer* layer = platformLayer())
     layer->setCompositorMutableProperties(properties);