Update TabCapturePerformanceTest to more accurately time captures.

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

Index: chrome/browser/extensions/api/tab_capture/tab_capture_performancetest.cc
diff --git a/chrome/browser/extensions/api/tab_capture/tab_capture_performancetest.cc b/chrome/browser/extensions/api/tab_capture/tab_capture_performancetest.cc
index a86e94ebfeb0c5a78e7a8692144ef4631259c6b5..b7fa51e31a3ab41533b0b9759288d0698215fd0f 100644
--- a/chrome/browser/extensions/api/tab_capture/tab_capture_performancetest.cc
+++ b/chrome/browser/extensions/api/tab_capture/tab_capture_performancetest.cc
@@ -202,12 +202,13 @@ class TabCapturePerformanceTest
         "ms");
     EXPECT_TRUE(gpu_frames);
 
-    // 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.
+    // 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. Note that we track the CaptureSucceeded event rather
+    // than Capture, as Capture only indicates that a capture was requested.
     EXPECT_TRUE(PrintResults(analyzer.get(),
                              test_name,
-                             "Capture",
+                             "CaptureSucceeded",

[hubbe, 2015/05/19 19:14:52]

How about printing out both results?
(Add a TODO to remove the "Capture" one in the future.)

[ericrk, 2015/05/19 20:02:08]

Good call - done.

                              "ms"));
   }
 };