Visually group dependency visualization class nodes by buildtarget

A convex hull is now created around nodes within the same buildtarget,
expanded outwards slightly, and rendered on the visualization. Each
buildtarget is a different color, and nodes are colored according to
their buildtarget. This feature can be turned off with a radio button UI
element.

To support this feature, the original node colorings have been changed
to outline colors.

Bug: 1106121
Change-Id: Idbb89a5010fa56bc6ac083c65e98d77930796127
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2316790
Reviewed-by: Mohamed Heikal <mheikal@chromium.org>
Reviewed-by: Samuel Huang <huangs@chromium.org>
Commit-Queue: James Long <yjlong@google.com>
Cr-Original-Commit-Position: refs/heads/master@{#792033}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 1b42d94ba11ac003533cc6eb983af141b074b123
5 files changed