Remove command line/field trial support and configs for Isolate Extensions.

content/browser/frame_host/frame_tree_browsertest.cc

Index: content/browser/frame_host/frame_tree_browsertest.cc
diff --git a/content/browser/frame_host/frame_tree_browsertest.cc b/content/browser/frame_host/frame_tree_browsertest.cc
index ee4aa82cb0530b5cc3354eefd5acc97fccf407a8..24feddd17a671295963c914148040c30d6ec2f85 100644
--- a/content/browser/frame_host/frame_tree_browsertest.cc
+++ b/content/browser/frame_host/frame_tree_browsertest.cc
@@ -699,10 +699,8 @@ IN_PROC_BROWSER_TEST_F(CrossProcessFrameTreeBrowserTest,
 }
 
 // FrameTreeBrowserTest variant where we isolate http://*.is, Iceland's top
-// level domain. This is an analogue to --isolate-extensions that we use inside
-// of content_browsertests, where extensions don't exist. Iceland, like an
-// extension process, is a special place with magical powers; we want to protect
-// it from outsiders.
+// level domain. Iceland is a special place with magical powers; we want to
+// protect it from outsiders :).

[ncarter (slow), 2017/05/01 20:15:19]

Removing the mention of 'extension' from this comment obscures the point
somewhat: which is that we're supposed to pretend that "*.is" is a stand-in for
extensions.

[nasko, 2017/05/01 21:25:37]

Done.

 class IsolateIcelandFrameTreeBrowserTest : public ContentBrowserTest {
  public:
   IsolateIcelandFrameTreeBrowserTest() {}