Remove ui::Gpu from SyncCallRestrictions friends.

I had changed ui::Gpu to not use ScopedAllowSyncCall previously. Remove
ui::Gpu from SyncCallRestrictions friends since it's not needed.

Bug: none
Change-Id: I8e0c80a87970882b83aec8de046e17fdb90e016f
Reviewed-on: https://chromium-review.googlesource.com/883766Reviewed-by: Ken Rockot <rockot@chromium.org>
Commit-Queue: kylechar <kylechar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#531750}

mojo/public/cpp/bindings/sync_call_restrictions.h

@@ -37,10 +37,6 @@ namespace prefs {
 class PersistentPrefStoreClient;
 }
 
-namespace ui {
-class Gpu;
-}
-
 namespace views {
 class ClipboardMus;
 }
@@ -75,7 +71,6 @@ class MOJO_CPP_BINDINGS_EXPORT SyncCallRestrictions {
   // DO NOT ADD ANY OTHER FRIEND STATEMENTS, talk to mojo/OWNERS first.
   // BEGIN ALLOWED USAGE.
   friend class content::BrowserTestBase;  // Test-only.
-  friend class ui::Gpu;  // http://crbug.com/620058
   // LevelDBMojoProxy makes same-process sync calls from the DB thread.
   friend class leveldb::LevelDBMojoProxy;
   // Pref service connection is sync at startup.

services/ui/public/cpp/gpu/gpu.cc

@@ -12,7 +12,6 @@
 #include "base/trace_event/trace_event.h"
 #include "build/build_config.h"
 #include "gpu/command_buffer/common/scheduling_priority.h"
-#include "mojo/public/cpp/bindings/sync_call_restrictions.h"
 #include "services/service_manager/public/cpp/connector.h"
 #include "services/ui/public/cpp/gpu/client_gpu_memory_buffer_manager.h"
 #include "services/ui/public/cpp/gpu/context_provider_command_buffer.h"