Remove all blimp browsertests.

base/threading/thread_restrictions.h

Index: base/threading/thread_restrictions.h
diff --git a/base/threading/thread_restrictions.h b/base/threading/thread_restrictions.h
index f0918cd7d9678e21bad2987271395677d95a08db..be917fd7d95b1039a13b9c610fc3a13ea7cf3e9a 100644
--- a/base/threading/thread_restrictions.h
+++ b/base/threading/thread_restrictions.h
@@ -14,9 +14,6 @@ class HistogramSynchronizer;
 class NativeBackendKWallet;
 class ScopedAllowWaitForLegacyWebViewApi;
 
-namespace blimp {
-class BlimpBrowserTest;
-}
 namespace cc {
 class CompletionEvent;
 class SingleThreadTaskGraphRunner;
@@ -174,7 +171,6 @@ class BASE_EXPORT ThreadRestrictions {
  private:
   // DO NOT ADD ANY OTHER FRIEND STATEMENTS, talk to jam or brettw first.
   // BEGIN ALLOWED USAGE.
-  friend class blimp::BlimpBrowserTest;
   friend class content::BrowserShutdownProfileDumper;
   friend class content::BrowserSurfaceViewManager;
   friend class content::BrowserTestBase;