[Browser/WebTaskEnvironment] Mass-migrate away from Test(Browser|Web)ThreadBundle

This is
 1) s/TestBrowserThreadBundle/BrowserTaskEnvironment/ on src/
 2) s/([^/])\b\w*thread_bundle(_)?/\1task_environment\2/ on files modified in (1)
 3) git cl format
 4) Manually fix up remainder "ThreadBundle" and "thread_bundle" found via
    string search on the whole of src/.

For ease of review:
 * Step #3 is the diff between patch sets 1..2
 * Step #4 is the diff between patch sets 2..3

[email protected]
(for post-review owners bypass per mechanical change)

Bug: 992483
Change-Id: I4945141f6d78bdc6c98444198e5012ddc8e5bff0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1758440
Reviewed-by: Gabriel Charette <[email protected]>
Reviewed-by: Daniel Cheng <[email protected]>
Commit-Queue: Gabriel Charette <[email protected]>
Auto-Submit: Gabriel Charette <[email protected]>
Cr-Commit-Position: refs/heads/master@{#688755}
diff --git a/chrome/browser/extensions/update_install_gate_unittest.cc b/chrome/browser/extensions/update_install_gate_unittest.cc
index bc20e82e..3dcc13a 100644
--- a/chrome/browser/extensions/update_install_gate_unittest.cc
+++ b/chrome/browser/extensions/update_install_gate_unittest.cc
@@ -201,7 +201,7 @@
 
  private:
   // Needed by extension system.
-  content::TestBrowserThreadBundle thread_bundle_;
+  content::BrowserTaskEnvironment task_environment_;
 
   // Needed to ensure we don't end up creating actual RenderViewHosts
   // and RenderProcessHosts.