Use skia.mojom.BitmapN32 in DeviceCursor mojoms

These bitmaps are safer for transport from untrustworthy sources since
all bitmaps should be in N32 format and the browser can make bad
assumptions as a result.

Bug: 1144462
Change-Id: Idf24a0cbb84fa884b67aa217e2ecc2cc0885d0a1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2575152
Auto-Submit: danakj <danakj@chromium.org>
Commit-Queue: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#833957}

ui/ozone/public/mojom/device_cursor.mojom

@@ -15,7 +15,7 @@ interface DeviceCursor {
   // Sets the cursor |bitmaps| on |window| at |point| with
   // |frame_delay_ms|.
   SetCursor(gfx.mojom.AcceleratedWidget window,
-            array<skia.mojom.BitmapWithArbitraryBpp> bitmaps,
+            array<skia.mojom.BitmapN32> bitmaps,
             gfx.mojom.Point point,
             int32 frame_delay_ms);