Remove usages of WebContents::GetRenderViewHost().

This CL was uploaded by git cl split.

R=chrisha@chromium.org

Bug: 1142671
Change-Id: Icc28a6f36e869729bdd87cbdf26243a9c7fcb71d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2500215
Auto-Submit: Lucas Gadani <lfg@chromium.org>
Reviewed-by: Chris Hamilton <chrisha@chromium.org>
Commit-Queue: Chris Hamilton <chrisha@chromium.org>
Cr-Commit-Position: refs/heads/master@{#821250}

components/performance_manager/graph/policies/process_priority_policy_unittest.cc

@@ -112,7 +112,7 @@ TEST_F(ProcessPriorityPolicyTest, GraphReflectedToRenderProcessHost) {
 
   // Set the active contents in the RenderViewHostTestHarness.
   SetContents(CreateTestWebContents());
-  auto* rvh = web_contents()->GetRenderViewHost();
+  auto* rvh = web_contents()->GetMainFrame()->GetRenderViewHost();
   DCHECK(rvh);
   auto* rph = rvh->GetProcess();
   DCHECK(rph);