gpu shader cache: Clarify lifetime/ownership/threadiness of objects.

content/browser/gpu/shader_disk_cache_unittest.cc

Index: content/browser/gpu/shader_disk_cache_unittest.cc
diff --git a/content/browser/gpu/shader_disk_cache_unittest.cc b/content/browser/gpu/shader_disk_cache_unittest.cc
index 53951e82104b82bdd2121bd8f36f9555d8852527..80629470a316ac7be24d394e26270b2228b82d33 100644
--- a/content/browser/gpu/shader_disk_cache_unittest.cc
+++ b/content/browser/gpu/shader_disk_cache_unittest.cc
@@ -5,6 +5,7 @@
 #include "base/files/scoped_temp_dir.h"
 #include "base/macros.h"
 #include "base/threading/thread.h"
+#include "base/threading/thread_task_runner_handle.h"
 #include "content/browser/browser_thread_impl.h"
 #include "content/browser/gpu/shader_disk_cache.h"
 #include "content/public/test/test_browser_thread_bundle.h"
@@ -24,6 +25,9 @@ class ShaderDiskCacheTest : public testing::Test {
  public:
   ShaderDiskCacheTest()
       : thread_bundle_(content::TestBrowserThreadBundle::IO_MAINLOOP) {
+    ShaderCacheFactory::InitInstance(
+        base::ThreadTaskRunnerHandle::Get(),
+        BrowserThread::GetTaskRunnerForThread(BrowserThread::CACHE));
   }
 
   ~ShaderDiskCacheTest() override {}