Default brave shield pref settings - Basic UI

[bbondy]

Test plan

1. Fresh profile
2. In tab 1, open chrome://settings and verify there is a new section Brave shields defaults
3. In tab 2, open https://dailymail.co.uk and verify ads are being blocked (visually and using shields menu)
4. In tab 1 (chrome://settings), set Ad Control to Allow ads and tracking
5. Refresh tab 2 (dailymail) and verify that ads are being shown (and that shields has 0 blocked)
6. Use the shields icon in the top right of the page and set Ad Control to Block ads
7. tab 2 will refresh itself after the change; verify that ads are being blocked again (which overrides the global setting)
8. Repeat the above steps for Cookie control, Fingerprinting protection, HTTPS Everywhere, and Script blocking

The above can be tested in a private window too- but it may not work because of a known issue which is captured here: #1198

Description

Have a global shield settings, similar to the one available in our Muon based product. We only need to implement the raw functionality. Updating the styling to match our brand is covered with #606

[bbondy]

[srirambv]

This fails on 0.55.10.

1. Setting Allow ads and tracking in global settings still blocks tracking scripts on shields
2. Changing shields settings to Allow ads and tracking sets count to 0

Here's the steps recording https://youtu.be/l75ZWlgbySA

[bbondy]

@srirambv can you try with a fresh page load and not a reload? Same results?

[srirambv]

With new page load in a new tab still same result. 3 tracking scripts are still blocked even if global shield settings is set to Allow ads and tracking.

[srirambv]

Verification Passed on

Brave	0.55.14 Chromium: 70.0.3538.54 (Official Build) beta(64-bit)
Revision	4f8e578b6680574714e9ed3bb9f02922b4dde40d-refs/branch-heads/3538@{#937}
OS	Linux

• Verified global settings can be overridden from shields
• Verified global settings take effect on a page when loaded

Verified passed with

Brave	0.55.14 Chromium: 70.0.3538.54 (Official Build) beta(64-bit)
Revision	4f8e578b6680574714e9ed3bb9f02922b4dde40d-refs/branch-heads/3538@{#937}
OS	Mac OS X

• Verified test plan from description. Global settings take effect on a page when loaded and can be overridden from shields.

Verification Passed on

Brave	0.55.16 Chromium: 70.0.3538.54 (Official Build) (64-bit)
Revision	4f8e578b6680574714e9ed3bb9f02922b4dde40d-refs/branch-heads/3538@{#937}
OS	Windows

• Verified test plan from description. Global settings take effect on a page when loaded and can be overridden from shields.