Using pre-existing constants instead of hard-coding

Constants for https, http already exists in our_constants. This patch makes gurl use those constants instead of hrad-coded values. Also it adds constants for WS and WSS.

Review URL: https://codereview.chromium.org/301353003

git-svn-id: https://src.chromium.org/chrome/trunk/src/url@274179 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
GN: //url should depend on //base/third_party/dynamic_annotations

It does in the gyp build and at least on mac not doing so leads to unresolved
symbols.

R=brettw@chromium.org

Review URL: https://codereview.chromium.org/313583006

git-svn-id: https://src.chromium.org/chrome/trunk/src/url@275026 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
Move kStandardSchemeSeparator from //content to //url

This constant is used in code shared by iOS, and is general enough to be placed
in //url.

TBR=benm,yoz

Review URL: https://codereview.chromium.org/319613002

git-svn-id: https://src.chromium.org/chrome/trunk/src/url@275055 4ff67af0-8c30-449e-8e8b-ad334ec8d88c