commit 9ee8292331413ec4dc1d773780fdcd045a1bb703
author Xinyi Ji <xinyiji@google.com> Tue Jun 03 17:29:19 2025
committer Chromium LUCI CQ <chromium-scoped@luci-project-accounts.iam.gserviceaccount.com> Tue Jun 03 17:29:19 2025
tree 904e54b20c9b610b9ad7c3c93a42db10e3cf6cef
parent 7d26c17702efa610f74e99147e4ed324921c329f

[NTP Customization] Add NTP Customization toolbar button (part 7)

This CL adds the NTP Customization toolbar button next to the Home
button by integrating it into ToolbarPhone. The timing of their
appearance is shown below:
1. When the current page is the NTP:
   a. If the homepage is disabled or set to the NTP, only the NTP
customization button will be shown.
   b. If the homepage is enabled and set to a different webpage, both
the Home button and the NTP customization button will be displayed.
2. When the current page is not the NTP:
   a. The NTP customization button will not be shown.
   b. The Home button will be shown only if the homepage is enabled.

As a result, there may be two buttons on the left side of the toolbar,
which can appear or disappear depending on the context. Therefore, we
deprecated the original Home button and replaced it with two list menu
buttons to manage their individual behavior. These buttons are centrally
managed by the HomePageButtonsCoordinator, which is created in the
ToolbarManager and passed into ToolbarPhone. The coordinator updates the
appearance of the two optional buttons based on changes such as the
visual state of ToolbarPhone or homepage updates. The final behavior is
shown below：https://drive.google.com/file/d/1fLqV27_lbo5gqWVqzTMI4_e9kmQXGaCI/view?
usp=sharing&resourcekey=0-qctOPf4qXh0iNjlVVbP9UA

To integrate the new home page buttons feature, which is controlled by a
flag, I've introduced a HomeButtonDisplay interface. This interface
helps encapsulate the logic for both the new buttons and the original
home button. Both the new HomePageButtonsCoordinator and the original
HomeButtonCoordinator implement this interface. The ToolbarManager is
responsible for creating both coordinators. It checks the flag to
determine which coordinator to use and then passes the selected one to
ToolbarPhone as a HomeButtonDisplay object. This approach centralizes
the feature flag logic, avoiding the need for checks throughout the
codebase.

Bug: 407554279
Change-Id: I4969b3d2ffa304d1b1db3d9c7b7bedf0a0783537
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6394955
Commit-Queue: Xinyi Ji <xinyiji@chromium.org>
Reviewed-by: Patrick Noland <pnoland@chromium.org>
Reviewed-by: Xi Han <hanxi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1468821}