Remove usages of WebContents::GetRenderViewHost().

This CL was uploaded by git cl split.

R=battre@chromium.org

Bug: 1142671
Change-Id: Ia5607ae4f0bcc78168077ac0a73b8c722473c4ef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2500554
Auto-Submit: Lucas Gadani <lfg@chromium.org>
Reviewed-by: Dominic Battré <battre@chromium.org>
Commit-Queue: Dominic Battré <battre@chromium.org>
Cr-Commit-Position: refs/heads/master@{#821126}

chrome/browser/extensions/api/web_request/web_request_apitest.cc

@@ -719,9 +719,11 @@ IN_PROC_BROWSER_TEST_F(ExtensionWebRequestApiTest, WebRequestNewTab) {
   mouse_event.button = blink::WebMouseEvent::Button::kLeft;
   mouse_event.SetPositionInWidget(7, 7);
   mouse_event.click_count = 1;
-  tab->GetRenderViewHost()->GetWidget()->ForwardMouseEvent(mouse_event);
+  tab->GetMainFrame()->GetRenderViewHost()->GetWidget()->ForwardMouseEvent(
+      mouse_event);
   mouse_event.SetType(blink::WebInputEvent::Type::kMouseUp);
-  tab->GetRenderViewHost()->GetWidget()->ForwardMouseEvent(mouse_event);
+  tab->GetMainFrame()->GetRenderViewHost()->GetWidget()->ForwardMouseEvent(
+      mouse_event);
 
   ASSERT_TRUE(catcher.GetNextResult()) << catcher.message();
 }