VR: Fix VRAutopresentedWebVR metric

We assumed that ui_initial_state.web_vr_autopresentation_expected and
initial_state.in_web_vr are mutually exclusive, which changed in
  https://chromium-review.googlesource.com/c/chromium/src/+/790890

Bug: None
Change-Id: I3141a75292d40a090166d2e656d559fcadb6cd0d
Reviewed-on: https://chromium-review.googlesource.com/924367Reviewed-by: Ian Vollick <vollick@chromium.org>
Commit-Queue: Yash Malik <ymalik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537412}

chrome/browser/android/vr_shell/vr_shell.cc

@@ -161,7 +161,8 @@ VrShell::VrShell(JNIEnv* env,
 
   if (ui_initial_state.in_web_vr ||
       ui_initial_state.web_vr_autopresentation_expected) {
-    UMA_HISTOGRAM_BOOLEAN("VRAutopresentedWebVR", !ui_initial_state.in_web_vr);
+    UMA_HISTOGRAM_BOOLEAN("VRAutopresentedWebVR",
+                          ui_initial_state.web_vr_autopresentation_expected);
   }
 
   AssetsLoader::GetInstance()->SetOnComponentReadyCallback(base::BindRepeating(