On my most recent browser actions buttons CL, pkasting@ suggested having a unified size for all toolbar buttons, which I think is a very good suggestion and will simplify the code a lot, but it will slightly change the existing behavior a bit:

- In the touchable chrome new design, we unified all button sizes to be 48x48 which is great, but for normal and hybrid modes, things are not unified. Consider the following:


For normal mode:
  1.a - buttons (back, forward, reload, home, menu) are 28x28 laid out side by side with no paddings.
  1.b - browser actions buttons are 28x28 with 4px paddings. By embedding the paddings inside the view's bounds (as suggested here: https://bugs.chromium.org/p/chromium/issues/detail?id=818034#c12), it makes the button 32x32.
  1.c - on Mac, browser actions buttons are 24x24 with 4px paddings. By embedding the paddings, the button becomes 28x28.

For hybrid mode:
  2.a - buttons (back, forward, reload, home, menu) are 28x28 with 8px paddings between each. If we embed the paddings, the buttons become 36x36.
  2.b- browser actions buttons are 28x28 with 8px paddings. By embedding the paddings, the buttons become 36x36, which matches (2.a) nicely.
  2.c - on Mac, browser actions buttons are 24x24 with 8px paddings. By embedding the paddings, the buttons become 32x32.

Given the above, I think we can unify the button sizes as follows for all platforms:
32x32 --> normal
36x36 --> hybrid
48x48 --> touchable.

But before, we need to check with someone from Chrome UX team.