Adding DRP specfic UMA for FirstContentfulPaint

content/public/test/test_renderer_host.h

Index: content/public/test/test_renderer_host.h
diff --git a/content/public/test/test_renderer_host.h b/content/public/test/test_renderer_host.h
index 062c642be91930d4e5305cd31cd56ff6a4da8380..e70d2f259a9a8b57b58a8470122d02f1393daa75 100644
--- a/content/public/test/test_renderer_host.h
+++ b/content/public/test/test_renderer_host.h
@@ -234,20 +234,22 @@ class RenderViewHostTestHarness : public testing::Test {
   void SetContents(WebContents* contents);
 
   // Creates a new test-enabled WebContents. Ownership passes to the
   // caller.
   WebContents* CreateTestWebContents();
 
   // Cover for |contents()->NavigateAndCommit(url)|. See
   // WebContentsTester::NavigateAndCommit for details.
   void NavigateAndCommit(const GURL& url);
 
+  void SetSimulateUsedDataReductionProxy(bool enabled);
+
   // Simulates a reload of the current page.
   void Reload();
   void FailedReload();
 
  protected:
   // testing::Test
   void SetUp() override;
   void TearDown() override;
 
   // Derived classes should override this method to use a custom BrowserContext.