Fix chrome password importing is failed on Win

[simonhong]

To read chrome's login data, chrome's encryption key is used.
To do this, fetching key from local prefs and set it in importing
service process.

Resolves brave/brave-browser#3674

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Verified that these changes build without errors on
  • Android
  • iOS
  • Linux
  • macOS
  • Windows
• Verified that these changes pass automated tests (unit, browser, security tests) on
  • iOS
  • Linux
  • macOS
  • Windows
• Verified that all lint errors/warnings are resolved (npm run lint)
• Ran git rebase master (if needed).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.
• Request a security/privacy review as needed.
• Add appropriate QA labels (QA/Yes or QA/No) to include the closed issue in milestone
• Public documentation has been updated as necessary. For instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protections
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-compatibility-issues-with-tracking-protection
  • https://github.com/brave/brave-browser/wiki/QA-Guide

Test Plan:

1. Launch browser and import chrome's password with brave://settings/importData.

2. Select Chrome profile (ensure that the Chrome profile has 2-3 passwords saved) and select Saved Passwords

3. Check Chrome's password is properly imported in brave://settings/passwords

4. Create a new profile.

5. On second screen of brave://welcome/ Import Bookmarks and Settings.

6. Choose Chrome profile in Import and Settings screen

7. Check Chrome's password is properly imported in brave://settings/passwords

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions
• Verify test plan is specified in PR before merging to source

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on.
• All relevant documentation has been updated.

[mkarolin]

LGTM

[kjozwiak]

Reproduced the original issue on Win 10 x64 using the following build:

Brave | 1.8.85 Chromium: 81.0.4044.122 (Official Build) (64-bit)
--- | ---
Revision | 44f4233f08910d83b146130c1938256a2e05b136-refs/branch-heads/4044@{#963}
OS | Windows 10 OS Version 1909 (Build 18363.815)

• attempted importing Chrome passwords via brave://settings/importData
• attempted importing Chrome passwords via brave://welcome/

Verification PASSED* on Win 10 x64 using the following build:

Brave | 1.10.11 Chromium: 81.0.4044.122 (Official Build) nightly (64-bit)
-- | --
Revision | 44f4233f08910d83b146130c1938256a2e05b136-refs/branch-heads/4044@{#963}
OS | Windows 10 OS Version 1909 (Build 18363.815)

Saved the following passwords under Chrome:

• ensured that importing passwords from Chrome via brave://settings/importData works
• ensured that importing passwords from Chrome via brave://welcome/ works
• ensured that Try Again worked when attempting to import from Chrome while it's opened
• ensured that cookies are not being imported
• ensured that History and Bookmarks are being imported

Passwords being imported from Chrome:

Ensuring that Try Again worked once Chrome is closed: