[Extensions Cleanup] Move ExtensionApiTest to extensions namespace

Move the ExtensionApiTest class into the extensions namespace, and
updated affected sites.

This CL should have no functional change.

Bug: 117261
[email protected] (/chrome)
[email protected] (/third_party/liblouis)

Change-Id: Ibd8820f47ebe53140fd725fb00b1d75c9872808c
Reviewed-on: https://chromium-review.googlesource.com/1050580
Commit-Queue: Devlin <[email protected]>
Reviewed-by: Istiaque Ahmed <[email protected]>
Cr-Commit-Position: refs/heads/master@{#558534}
diff --git a/chrome/browser/extensions/shared_module_apitest.cc b/chrome/browser/extensions/shared_module_apitest.cc
index 9292c98c..edf70b4 100644
--- a/chrome/browser/extensions/shared_module_apitest.cc
+++ b/chrome/browser/extensions/shared_module_apitest.cc
@@ -5,7 +5,7 @@
 #include "chrome/browser/extensions/extension_apitest.h"
 #include "extensions/test/extension_test_message_listener.h"
 
-using extensions::Extension;
+namespace extensions {
 
 // NB: We use LoadExtension instead of InstallExtension for shared modules so
 // the public-keys in their manifests are used to generate the extension ID, so
@@ -55,3 +55,5 @@
 
   EXPECT_TRUE(RunExtensionTest("shared_module/import_locales"));
 }
+
+}  // namespace extensions