Revert of Add ExtensionsApiClient interface, use it in the storage API SettingsFrontend

Revert of Add ExtensionsApiClient interface, use it in the storage API SettingsFrontend (https://codereview.chromium.org/180213008/)

Reason for revert:
Likely broke GCMProfileServiceSingleProfileTest.Unregister Android.

Original issue's description:
> Add ExtensionsApiClient interface, use it in the storage API SettingsFrontend
> 
> app_shell needs the chrome.storage.local extension API so the core storage implementation is moving to //extensions/browser/api. However, the "managed storage" API implementation needs to remain in Chrome.
> 
> * Introduce ExtensionsApiClient in extensions/browser/api
> * Introduce ChromeExtensionsApiClient in chrome/browser/extensions/api
> * Delegate out the storage ManagedValueStoreCache creation to Chrome
> * Move settings_namespace.h/cc to e/b/api/storage so we can use an enum in the client interface definition
> 
> Most APIs will probably need to make only one or two client interface calls, so we're starting with a single ExtensionsApiClient interface. It we find individual APIs tend to need a lot of methods we can split it into one client interface per API, but that seems like overkill right now.
> 
> BUG=348058
> TEST=unit_tests *Settings* and browser_tests ExtensionSettings*
> R=rdevlin.cronin@chromium.org, rockot@chromium.org, yoz@chromium.org
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=255069

TBR=rdevlin.cronin@chromium.org,rockot@chromium.org,yoz@chromium.org,jamescook@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=348058

[Nico, 2014-03-05 19:37:06]

Created Revert of Add ExtensionsApiClient interface, use it in the storage API
SettingsFrontend

[commit-bot: I haz the power, 2014-03-05 19:38:04]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/thakis@chromium.org/181233011/1

[commit-bot: I haz the power, 2014-03-05 19:38:11]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-03-05 19:38:12]

Failed to apply patch for
chrome/browser/extensions/api/storage/settings_frontend.h:
While running patch -p1 --forward --force --no-backup-if-mismatch;
  patching file chrome/browser/extensions/api/storage/settings_frontend.h
  Hunk #1 FAILED at 11.
  1 out of 1 hunk FAILED -- saving rejects to file
chrome/browser/extensions/api/storage/settings_frontend.h.rej

Patch:       chrome/browser/extensions/api/storage/settings_frontend.h
Index: chrome/browser/extensions/api/storage/settings_frontend.h
diff --git a/chrome/browser/extensions/api/storage/settings_frontend.h
b/chrome/browser/extensions/api/storage/settings_frontend.h
index
70a52c48a54d2cc295a30dfa744f5da1e8f1ac87..abda6c854b7f21d4a44690e3bbfaf1051438d577
100644
--- a/chrome/browser/extensions/api/storage/settings_frontend.h
+++ b/chrome/browser/extensions/api/storage/settings_frontend.h
@@ -11,11 +11,11 @@
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/extensions/api/profile_keyed_api_factory.h"
+#include "chrome/browser/extensions/api/storage/settings_namespace.h"
 #include "chrome/browser/extensions/api/storage/settings_observer.h"
 #include "chrome/browser/extensions/api/storage/settings_storage_factory.h"
 #include
"chrome/browser/extensions/api/storage/settings_storage_quota_enforcer.h"
 #include "chrome/browser/extensions/api/storage/value_store_cache.h"
-#include "extensions/browser/api/storage/settings_namespace.h"
 #include "sync/api/syncable_service.h"
 
 namespace content {