Ensuring interception of stream get determined by plugin path before checking mime type.

content/test/fake_plugin_service.h

Index: content/test/fake_plugin_service.h
diff --git a/content/test/fake_plugin_service.h b/content/test/fake_plugin_service.h
index ed8450cba5672be69c39c143a8cd6703c37e8b2b..fa614ee3c8dc329790920a7f758a087702e7b150 100644
--- a/content/test/fake_plugin_service.h
+++ b/content/test/fake_plugin_service.h
@@ -13,6 +13,7 @@ namespace content {
 class FakePluginService : public PluginService {
  public:
   FakePluginService();
+  FakePluginService(bool is_plugin_available);
   ~FakePluginService() override;
   // PluginService implementation:
   void Init() override;
@@ -65,6 +66,7 @@ class FakePluginService : public PluginService {
                                 const GURL& document_url) override;
 
  private:
+  bool is_plugin_available_;
   DISALLOW_COPY_AND_ASSIGN(FakePluginService);
 };