content: Re-enable ChildDiscardableSharedMemoryManager browser tests on ChromeOS.

content/child/child_discardable_shared_memory_manager_browsertest.cc

 // Copyright 2015 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 "base/bind.h"
 #include "base/command_line.h"
 #include "content/child/child_discardable_shared_memory_manager.h"
 #include "content/child/child_thread_impl.h"
 #include "content/common/host_discardable_shared_memory_manager.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/test/content_browser_test.h"
 #include "content/public/test/content_browser_test_utils.h"
 #include "content/shell/browser/shell.h"
 #include "url/gurl.h"
 
 namespace content {
 
-// ChromeOS does not do software compositing, so kDisableGpu is not available
-// there.
-#if !defined(OS_CHROMEOS)
-
 class ChildDiscardableSharedMemoryManagerBrowserTest
     : public ContentBrowserTest {
  public:
   void SetUpCommandLine(base::CommandLine* command_line) override {
     command_line->AppendSwitch(switches::kSingleProcess);
-    command_line->AppendSwitch(switches::kDisableGpu);
   }
 
   static void ReleaseFreeMemory() {
     ChildThreadImpl::current()
         ->discardable_shared_memory_manager()
         ->ReleaseFreeMemory();
   }
 
   static void AllocateLockedMemory(
       size_t size,
@@ skipping 77 matching lines @@
         memory.get()));
   }
 
   for (auto& memory : instances) {
     PostTaskToInProcessRendererAndWait(
         base::Bind(&ChildDiscardableSharedMemoryManagerBrowserTest::FreeMemory,
                    base::Passed(&memory)));
   }
 }
 
-#endif  // !OS_CHROMEOS
-
 }  // content