Don't recapture thumbnails on fully loaded pages

The thumbnail scheduler implementation introduced a bug: each time a
ThumbnailImage is observed, ThumbnailCaptureDriver will recapture the
thumbnail even though it already has a good final capture.

This CL fixes the regression.

Fixed: 1136247
Change-Id: I825632157802eda70656f9fdb4376942b5febe15
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2459627
Auto-Submit: Collin Baker <collinbaker@chromium.org>
Reviewed-by: Dana Fried <dfried@chromium.org>
Commit-Queue: Collin Baker <collinbaker@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815299}

chrome/browser/ui/thumbnails/thumbnail_capture_driver.cc

@@ -56,7 +56,10 @@ void ThumbnailCaptureDriver::SetCapturePermittedByScheduler(bool scheduled) {
 void ThumbnailCaptureDriver::UpdateCaptureState() {
   if (!scheduled_) {
     client_->StopCapture();
-    capture_state_ = CaptureState::kNoCapture;
+
+    if (capture_state_ < CaptureState::kHaveFinalCapture)
+      capture_state_ = CaptureState::kNoCapture;
+
     return;
   }
 

chrome/browser/ui/thumbnails/thumbnail_capture_driver_unittest.cc

@@ -486,3 +486,43 @@ TEST_F(ThumbnailCaptureDriverTest, StopsCaptureAtRetryLimit) {
   EXPECT_EQ(scheduler_.priority(),
             ThumbnailScheduler::TabCapturePriority::kNone);
 }
+
+TEST_F(ThumbnailCaptureDriverTest, DoesNotReCaptureAfterFinalThumbnail) {
+  {
+    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());
+  }
+
+  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);
+
+  capture_driver_.SetCapturePermittedByScheduler(false);
+
+  capture_driver_.UpdateThumbnailVisibility(false);
+  EXPECT_EQ(scheduler_.priority(),
+            ThumbnailScheduler::TabCapturePriority::kNone);
+
+  capture_driver_.UpdateThumbnailVisibility(true);
+  EXPECT_EQ(scheduler_.priority(),
+            ThumbnailScheduler::TabCapturePriority::kNone);
+}