Regenerate latest chrome.js and chrome_extensions.js

Steps:
1. Run third_party/closure_compiler/roll_closure_compiler
2. Remove newly added chrome.fileSystemProvider lines (conflicts with definitions in third_party/closure_compiler/externs/file_system_provider.js)
2. Revert README.chromium

Change-Id: I3e7dab78b8694e25e53d20661528a093f13c9844
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2461053
Commit-Queue: calamity <calamity@chromium.org>
Reviewed-by: calamity <calamity@chromium.org>
Auto-Submit: Josiah Krutz <josiahk@google.com>
Cr-Commit-Position: refs/heads/master@{#816430}

third_party/closure_compiler/externs/chrome.js

@@ -486,6 +486,10 @@ Tab.prototype.mutedInfo;
 Tab.prototype.url;
 
 
+/** @type {string|undefined} */
+Tab.prototype.pendingUrl;
+
+
 // TODO: Make this field optional once dependent projects have been updated.
 /** @type {string} */
 Tab.prototype.title;