fix: draw smoothing round rect corner

[cucbin]

Description of Change

Closes #48581

If my understanding is correct, the parameters of this method:

electron/shell/renderer/electron_smooth_round_rect.cc

Lines 102 to 107 in 26759b8

	void DrawCorner(SkPath& path,
	float radius,
	float smoothness1,
	float smoothness2,
	const SkPoint& corner,
	unsigned int quarter_rotations) {

smoothness1: Smoothness of the entry angle - controls the smoothness of the curve transitioning from the previous edge to the arc;
smoothness2: Smoothness of the exit angle - controls the smoothness of the curve transitioning from the arc to the next edge.

Taking the top left corner as:

• smoothness1 = left_top_smoothness ← from the left side
• smoothness2 = top_left_smoothness ← going to the top edge

Taking the top right corner as:

• smoothness1 = top_right_smoothness ← from the top edge
• smoothness2 = right_top_smoothness ← going to the right side

        top_left_smoothness (smoothness2)
    ←------------------------→
   ↑ ┌────────────o~~~~~~~~╮
   │ │                     ║
   │ │                     ║ ← right_top_smoothness (smoothness2)
   │ o                     o
   │ ║                     ║
   │ ║                     ║
   ↓ ║                     ║
left_top_smoothness      right_bottom_smoothness
   (smoothness1)            (smoothness1)

electron/shell/renderer/electron_smooth_round_rect.cc

Lines 292 to 298 in 26759b8

	// Top left corner
	DrawCorner(path, top_left_radius, left_top_smoothness, top_left_smoothness,
	SkPoint::Make(x, y), 0);
	// Top right corner
	DrawCorner(path, top_right_radius, top_right_smoothness, right_top_smoothness,
	SkPoint::Make(x + width, y), 1);

Therefore, the fourth corner should take from the bottom edge to the left.

• smoothness1 = bottom_left_smoothness ← from the bottom edge
• smoothness2 = left_bottom_smoothness ← going to the lefe side

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• tests are changed or added
• relevant API documentation, tutorials, and examples are updated and follow the documentation style guide
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: Fixed draw smoothing round corner issue

[codebytere]

@cucbin could you please write a PR body? What was the underlying issue and how does this fix it? In general we expect a PR body for all PRs, as it makes gathering context and performing effective review more frictionless for maintainers.

[jkleinsc]

• Nice find @cucbin. I have verified that this resolves #48581 and it doesn't regress the work done in #46751

[ckerr]

Nice writeup too. Thanks @cucbin

[release-clerk]

Release Notes Persisted

Fixed draw smoothing round corner issue

[trop]

I have automatically backported this PR to "38-x-y", please check out #48780

[trop]

I have automatically backported this PR to "39-x-y", please check out #48781

[trop]

I have automatically backported this PR to "40-x-y", please check out #48782

[trop]

I have automatically backported this PR to "37-x-y", please check out #48783