Remove usages of WebContents::GetRenderViewHost().

This CL was uploaded by git cl split.

R=hbos@chromium.org

Bug: 1142671
Change-Id: Iaa2a3bf794e1a8887c62c9c5059f58697ab219dc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2500488
Auto-Submit: Lucas Gadani <lfg@chromium.org>
Reviewed-by: Henrik Boström <hbos@chromium.org>
Commit-Queue: Henrik Boström <hbos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#821145}

chrome/browser/media/webrtc/webrtc_video_display_perf_browsertest.cc

@@ -229,8 +229,11 @@ class WebRtcVideoDisplayPerfBrowserTest
         OpenPageAndGetUserMediaInNewTabWithConstraints(
             embedded_test_server()->GetURL(kMainWebrtcTestHtmlPage),
             "{audio: true, video: false}");
-    const int process_id =
-        right_tab->GetRenderViewHost()->GetProcess()->GetProcess().Pid();
+    const int process_id = right_tab->GetMainFrame()
+                               ->GetRenderViewHost()
+                               ->GetProcess()
+                               ->GetProcess()
+                               .Pid();
 
     const std::string disable_cpu_adaptation_constraint(
         "{'optional': [{'googCpuOveruseDetection': false}]}");