Suppress WebRtcCaptureFromElementBrowserTest.VerifyCanvasCaptureOffscreenCanvasFrames on Win10

Looks like they're flaky (in viz_content_browsertests).

TBR=niklase

Bug: 869723
Change-Id: I8c2ea517fddfddb3f664107d0dc237fc3579c704
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/1157733
Commit-Queue: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579669}

content/browser/webrtc/webrtc_capture_from_element_browsertest.cc

@@ -109,8 +109,17 @@ IN_PROC_BROWSER_TEST_F(WebRtcCaptureFromElementBrowserTest,
   MakeTypicalCall("testCanvasCapture(drawWebGL);", kCanvasCaptureTestHtmlFile);
 }
 
+#if defined(OS_WIN)
+// https://crbug.com/869723
+// Flaky on Windows 10 with Viz (i.e. in viz_content_browsertests).
+#define MAYBE_VerifyCanvasCaptureOffscreenCanvasFrames \
+  DISABLED_VerifyCanvasCaptureOffscreenCanvasFrames
+#else
+#define MAYBE_VerifyCanvasCaptureOffscreenCanvasFrames \
+  VerifyCanvasCaptureOffscreenCanvasFrames
+#endif
 IN_PROC_BROWSER_TEST_F(WebRtcCaptureFromElementBrowserTest,
-                       VerifyCanvasCaptureOffscreenCanvasFrames) {
+                       MAYBE_VerifyCanvasCaptureOffscreenCanvasFrames) {
   MakeTypicalCall("testCanvasCapture(drawOffscreenCanvas);",
                   kCanvasCaptureTestHtmlFile);
 }