Create only one ContextFactory in content unit tests

content/browser/renderer_host/render_widget_host_view_mac_unittest.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/render_widget_host_view_mac.h"
 
 #include <Cocoa/Cocoa.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <tuple>
@@ skipping 223 matching lines @@
 }
 
 }  // namespace
 
 class RenderWidgetHostViewMacTest : public RenderViewHostImplTestHarness {
  public:
   RenderWidgetHostViewMacTest() : old_rwhv_(NULL), rwhv_mac_(NULL) {}
 
   void SetUp() override {
     RenderViewHostImplTestHarness::SetUp();
-    ImageTransportFactory::InitializeForUnitTests(
-        std::unique_ptr<ImageTransportFactory>(
-            new NoTransportImageTransportFactory));
-
     // TestRenderViewHost's destruction assumes that its view is a
     // TestRenderWidgetHostView, so store its view and reset it back to the
     // stored view in |TearDown()|.
     old_rwhv_ = rvh()->GetWidget()->GetView();
 
     // Owned by its |cocoa_view()|, i.e. |rwhv_cocoa_|.
     rwhv_mac_ = new RenderWidgetHostViewMac(rvh()->GetWidget(), false);
     rwhv_cocoa_.reset([rwhv_mac_->cocoa_view() retain]);
   }
   void TearDown() override {
     // Make sure the rwhv_mac_ is gone once the superclass's |TearDown()| runs.
     rwhv_cocoa_.reset();
     RecycleAndWait();
 
     // See comment in SetUp().
     test_rvh()->GetWidget()->SetView(
         static_cast<RenderWidgetHostViewBase*>(old_rwhv_));
 
-    ImageTransportFactory::Terminate();
     RenderViewHostImplTestHarness::TearDown();
   }
 
   void RecycleAndWait() {
     pool_.Recycle();
     base::RunLoop().RunUntilIdle();
     pool_.Recycle();
   }
 
   void DestroyHostViewRetainCocoaView() {
@@ skipping 965 matching lines @@
   // Verify that Event.Latency.OS.MOUSE_WHEEL histogram is computed properly.
   NSEvent* wheelEvent = MockScrollWheelEventWithPhase(@selector(phaseBegan),3);
   [view->cocoa_view() scrollWheel:wheelEvent];
   histogram_tester.ExpectTotalCount("Event.Latency.OS.MOUSE_WHEEL", 1);
 
   // Clean up.
   host->ShutdownAndDestroyWidget(true);
 }
 
 }  // namespace content