Invalidate thumbnail when a tab navigates to a new page

This behavior broke in a recent change, causing stale thumbnails and a
DCHECK in enabled builds.

Fixed: 1137330
Bug: 1136247
Change-Id: I70bee4d25e2c0693bcf55fe95dc2744dfb354456
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2464785Reviewed-by: Peter Boström <pbos@chromium.org>
Commit-Queue: Collin Baker <collinbaker@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816305}

chrome/browser/ui/thumbnails/thumbnail_capture_driver.cc

@@ -54,6 +54,15 @@ void ThumbnailCaptureDriver::SetCapturePermittedByScheduler(bool scheduled) {
 }
 
 void ThumbnailCaptureDriver::UpdateCaptureState() {
+  // If there was a final thumbnail but the page has changed, get set up
+  // for a new capture.
+  if (page_readiness_ < PageReadiness::kReadyForFinalCapture &&
+      capture_state_ == CaptureState::kHaveFinalCapture) {
+    client_->StopCapture();
+    capture_state_ = CaptureState::kNoCapture;
+  }
+
+  // If de-scheduled, stop any ongoing capture.
   if (!scheduled_) {
     client_->StopCapture();
 

chrome/browser/ui/thumbnails/thumbnail_capture_driver_unittest.cc

@@ -526,3 +526,58 @@ TEST_F(ThumbnailCaptureDriverTest, DoesNotReCaptureAfterFinalThumbnail) {
   EXPECT_EQ(scheduler_.priority(),
             ThumbnailScheduler::TabCapturePriority::kNone);
 }
+
+// Going from kReadyForFinalCapture to a lower readiness should always
+// invalidate the current thumbnail. Capture should restart from
+// scratch. Regression test for https://crbug.com/1137330
+TEST_F(ThumbnailCaptureDriverTest, InvalidatesThumbnailOnReadinessDecrease) {
+  {
+    InSequence s;
+    EXPECT_CALL(mock_client_, StopCapture()).Times(AnyNumber());
+    EXPECT_CALL(mock_client_, RequestCapture());
+    EXPECT_CALL(mock_client_, StartCapture());
+    EXPECT_CALL(mock_client_, StopCapture()).Times(AnyNumber());
+    EXPECT_CALL(mock_client_, RequestCapture());
+    EXPECT_CALL(mock_client_, StartCapture());
+  }
+
+  capture_driver_.UpdateThumbnailVisibility(true);
+  capture_driver_.UpdatePageVisibility(false);
+
+  capture_driver_.UpdatePageReadiness(
+      ThumbnailReadinessTracker::Readiness::kNotReady);
+  capture_driver_.UpdatePageReadiness(
+      ThumbnailReadinessTracker::Readiness::kReadyForInitialCapture);
+  capture_driver_.SetCapturePermittedByScheduler(true);
+  capture_driver_.SetCanCapture(true);
+  capture_driver_.UpdatePageReadiness(
+      ThumbnailReadinessTracker::Readiness::kReadyForFinalCapture);
+  EXPECT_EQ(scheduler_.priority(),
+            ThumbnailScheduler::TabCapturePriority::kHigh);
+
+  capture_driver_.SetCapturePermittedByScheduler(true);
+  capture_driver_.GotFrame();
+  task_environment_.FastForwardBy(ThumbnailCaptureDriver::kCooldownDelay);
+  EXPECT_EQ(scheduler_.priority(),
+            ThumbnailScheduler::TabCapturePriority::kNone);
+
+  // This should result in the thumbnail being invalidated. Subsequent
+  // loading should trigger capture again.
+  capture_driver_.UpdatePageReadiness(
+      ThumbnailReadinessTracker::Readiness::kNotReady);
+  EXPECT_EQ(scheduler_.priority(),
+            ThumbnailScheduler::TabCapturePriority::kNone);
+
+  capture_driver_.UpdatePageReadiness(
+      ThumbnailReadinessTracker::Readiness::kReadyForInitialCapture);
+  EXPECT_EQ(scheduler_.priority(),
+            ThumbnailScheduler::TabCapturePriority::kLow);
+
+  capture_driver_.SetCapturePermittedByScheduler(true);
+  capture_driver_.SetCanCapture(true);
+
+  capture_driver_.UpdatePageReadiness(
+      ThumbnailReadinessTracker::Readiness::kReadyForFinalCapture);
+  EXPECT_EQ(scheduler_.priority(),
+            ThumbnailScheduler::TabCapturePriority::kHigh);
+}