While working on a patch for bug 1645954 I discovered that the code here triggers multiple
ResizeReflow calls on the top-level presShell, and with different sizes. This happens (as far as I can tell) only on Android, and can be seen when running the geckoview-junit tests.
This seems undesirable for performance reasons if nothing else. This bug is to investigate why that's happening. Once the patches for bug 1645954 land, it can be reproduced by removing the
ifdef guard around the
AutoResizeReflowSquasher those patches add to
BrowserChild::RecvUpdateDimensions, and running the geckoview-junit suite.