Update TabCapturePerformanceTest to more accurately time captures.

Currently TabCapturePerformanceTest records the time between "Capture"
events to determine the rate of capture. These events are issued whenever
a capture is requested, even if it is later aborted, and doesn't represent
the actual capture framerate. This CL adds an event on capture
success which will provide a more accurate idea of capture framerate.

BUG=489796

Review URL: https://codereview.chromium.org/1143723003

Cr-Commit-Position: refs/heads/master@{#330785}

chrome/browser/extensions/api/tab_capture/tab_capture_performancetest.cc

@@ -205,10 +205,18 @@ class TabCapturePerformanceTest
     // This prints out the average time between capture events.
     // As the capture frame rate is capped at 30fps, this score
     // cannot get any better than (lower) 33.33 ms.
+    // TODO(ericrk): Remove the "Capture" result once we are confident that
+    // "CaptureSucceeded" is giving the coverage we want. crbug.com/489817
     EXPECT_TRUE(PrintResults(analyzer.get(),
                              test_name,
                              "Capture",
                              "ms"));
+
+    // Also track the CaptureSucceeded event. Capture only indicates that a
+    // capture was requested, but this capture may later be aborted without
+    // running. CaptureSucceeded tracks successful frame captures.
+    EXPECT_TRUE(
+        PrintResults(analyzer.get(), test_name, "CaptureSucceeded", "ms"));
   }
 };
 

content/browser/media/capture/content_video_capture_device_core.cc

@@ -182,6 +182,9 @@ void ThreadSafeCaptureOracle::DidCaptureFrame(
 
   if (success) {
     if (oracle_.CompleteCapture(frame_number, &timestamp)) {
+      TRACE_EVENT_INSTANT0("gpu.capture", "CaptureSucceeded",
+                           TRACE_EVENT_SCOPE_THREAD);
+
       frame->metadata()->SetDouble(media::VideoFrameMetadata::FRAME_RATE,
                                    params_.requested_format.frame_rate);
       frame->metadata()->SetTimeTicks(