Fix the crash in LiteVideoObserver

(i) If the mainframe is ineligible (e.g., if it's a non-http/https)
page, then skip recording metrics.

(ii) Update main frame navigation ID on same-document main frame
navigations

Bug: 1109068
Change-Id: I839393b607b6c2d090ff75ae927be7049fa4cd69
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2317167Reviewed-by: Michael Crouse <mcrouse@chromium.org>
Commit-Queue: Tarun Bansal <tbansal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791425}

chrome/browser/lite_video/lite_video_observer.cc

@@ -79,8 +79,12 @@ void LiteVideoObserver::DidStartNavigation(
 void LiteVideoObserver::DidFinishNavigation(
     content::NavigationHandle* navigation_handle) {
   DCHECK(navigation_handle);
+
+  if (navigation_handle->IsInMainFrame()) {
+    ineligible_main_frame_ = !navigation_handle->HasCommitted() ||
+                             !navigation_handle->GetURL().SchemeIsHTTPOrHTTPS();
+  }
   if (!navigation_handle->HasCommitted() ||
-      navigation_handle->IsSameDocument() ||
       !navigation_handle->GetURL().SchemeIsHTTPOrHTTPS()) {
     return;
   }
@@ -148,7 +152,12 @@ lite_video::LiteVideoDecision LiteVideoObserver::MakeLiteVideoDecision(
 void LiteVideoObserver::RecordUKMMetrics(
     lite_video::LiteVideoDecision decision,
     lite_video::LiteVideoBlocklistReason blocklist_reason) {
-  DCHECK(current_mainframe_navigation_id_);
+  // |current_mainframe_navigation_id_| may be null (e.g., if the mainframe was
+  // non-http/https).
+  DCHECK(current_mainframe_navigation_id_ || ineligible_main_frame_);
+  if (!current_mainframe_navigation_id_) {
+    return;
+  }
   ukm::SourceId ukm_source_id = ukm::ConvertToSourceId(
       *current_mainframe_navigation_id_, ukm::SourceIdType::NAVIGATION_ID);
   ukm::builders::LiteVideo builder(ukm_source_id);

chrome/browser/lite_video/lite_video_observer.h

@@ -64,7 +64,8 @@ class LiteVideoObserver
       base::Optional<lite_video::LiteVideoHint> hint) const;
 
   // Records the metrics for LiteVideos applied to any frames associated with
-  // the current mainframe navigation id. Called once per frame.
+  // the current mainframe navigation id. Called once per frame. Also, called
+  // for frames in the same document navigations.
   void RecordUKMMetrics(lite_video::LiteVideoDecision decision,
                         lite_video::LiteVideoBlocklistReason blocklist_reason);
 
@@ -82,6 +83,9 @@ class LiteVideoObserver
   // commits.
   bool is_coinflip_holdback_ = false;
 
+  // True if the main frame was not eligible for LiteVideo.
+  bool ineligible_main_frame_ = false;
+
   WEB_CONTENTS_USER_DATA_KEY_DECL();
 };