Call CanCaptureVisiblePage in page capture API.

Currently the pageCapture permission allows access
to arbitrary local files and chrome:// pages which
can be a security concern. In order to address this,
the page capture API needs to be changed similar to
the captureVisibleTab API. The API will now only allow
extensions to capture otherwise-restricted URLs if the
user has granted activeTab. In addition, file:// URLs are
only capturable with the "Allow on file URLs" option enabled.

Bug: 893087

Change-Id: I6d6225a3efb70fc033e2e1c031c633869afac624
Reviewed-on: https://chromium-review.googlesource.com/c/1330689
Commit-Queue: Bettina Dea <bdea@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Reviewed-by: Varun Khaneja <vakh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615248}
ExtensionFunction::ResponseValue TabsUpdateFunction::GetResult() {
  if (!has_callback())
    return NoArguments();

  return ArgumentList(
      tabs::Get::Results::Create(*ExtensionTabUtil::CreateTabObject(
          web_contents_, ExtensionTabUtil::kScrubTab, extension())));
}

ExtensionFunction::ResponseValue TabsUpdateFunction::GetResult() {
  if (!has_callback())
    return NoArguments();

  return ArgumentList(
      tabs::Get::Results::Create(*ExtensionTabUtil::CreateTabObject(
          web_contents_, ExtensionTabUtil::kScrubTab, extension())));
}
