feat : Add Partial Custom Tabs support (bottom sheet & side sheet)

[subhankarmaiti]

Adds support for Partial Custom Tabs, allowing the browser-based authentication flow to render as a bottom sheet or side sheet instead of taking over the full screen. Requires Chrome 107+; gracefully falls back to full-screen Custom Tabs on unsupported browsers.

API Changes

Six new methods on CustomTabsOptions.Builder:

Method	Description
withInitialHeight(int height)	Sets the bottom sheet height in dp. Minimum enforced by Chrome is 50% of screen.
withInitialWidth(int width)	Sets the side sheet width in dp (for wider screens).
withResizable(boolean resizable)	Locks or unlocks user-resizing of the sheet. Default: resizable.
withToolbarCornerRadius(int cornerRadius)	Sets toolbar top corner radius in dp. Only applies in bottom sheet mode.
withSideSheetBreakpoint(int breakpoint)	Breakpoint in dp to toggle between bottom sheet and side sheet. Browser default is typically 840dp.
withBackgroundInteractionEnabled(boolean enabled)	Allows tapping the background app while the partial tab is visible. Default: disabled.

All dimension parameters accept dp values. Height and width are converted to pixels internally via dpToPx().

Usage — Bottom Sheet

CustomTabsOptions options = CustomTabsOptions.newBuilder()
    .withInitialHeight(500)
    .withToolbarCornerRadius(16)
    .withResizable(false)
    .build();

WebAuthProvider.login(account)
    .withCustomTabsOptions(options)
    .start(context, callback);

Usage — Side Sheet on larger screens

CustomTabsOptions options = CustomTabsOptions.newBuilder()
    .withInitialHeight(500)
    .withInitialWidth(400)
    .withSideSheetBreakpoint(800)
    .withToolbarCornerRadius(10)
    .withResizable(false)
    .build();

WebAuthProvider.login(account)
    .withCustomTabsOptions(options)
    .start(context, callback);