Don't track main frames in web tests that are still provisional

Once they are swapped in, we can track and use them as the main frame.

R=avi@chromium.org

Bug: 1114382
Change-Id: I8f0b8c906a9dd5dd106dc1dc444aa24af4721347
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2378447
Auto-Submit: danakj <danakj@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#801942}

content/shell/renderer/web_test/test_runner.cc

@@ -2608,6 +2608,7 @@ class WorkItemBackForward : public TestRunner::WorkItem {
 WebFrameTestProxy* TestRunner::FindInProcessMainWindowMainFrame() {
   for (WebFrameTestProxy* main_frame : main_frames_) {
     WebViewTestProxy* view = main_frame->GetWebViewTestProxy();
+    DCHECK_EQ(view->GetMainRenderFrame(), main_frame);
     if (view->blink_test_runner()->is_main_window())
       return main_frame;
   }

content/shell/renderer/web_test/web_frame_test_proxy.cc

@@ -171,6 +171,10 @@ class TestRenderFrameObserver : public RenderFrameObserver {
     }
 
     if (render_frame()->IsMainFrame()) {
+      // Track main frames once they are swapped in, if they started
+      // provisional.
+      test_runner()->AddMainFrame(frame_proxy());
+
       // Looking for navigations to about:blank after a test completes.
       blink_test_runner()->DidCommitNavigationInMainFrame();
     }
@@ -234,7 +238,9 @@ void WebFrameTestProxy::Initialize(blink::WebFrame* parent) {
   RenderFrameImpl::Initialize(parent);
 
   TestRunner* test_runner = web_view_test_proxy_->GetTestRunner();
-  if (IsMainFrame())
+  // Track main frames if they started in the frame tree. Otherwise they are
+  // provisional and will be tracked once swapped in.
+  if (IsMainFrame() && in_frame_tree())
     test_runner->AddMainFrame(this);
 
   GetWebFrame()->SetContentSettingsClient(test_runner->GetWebContentSettings());