Re-enable previously flaking Viz tests

A few tests had been flaking on viz configs. Some have since shown themselves to
be flaking everywhere. Others have been triaged to have been caused by now fixed
issues.

This change updates the filter to re-enable one on viz_browser_tests. While only
re-enabling some on the FYI bot for viz_content_browsertests.

TBR=kylerchar@chromium.org
TEST=viz_browser_tests, viz_content_browsertests

Bug: 760181
Change-Id: I08e643dd8074ab3b7a4d6bbbe72063da81d21b04
Reviewed-on: https://chromium-review.googlesource.com/961262Reviewed-by: Jonathan Ross <jonross@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542900}

testing/buildbot/filters/mojo.fyi.viz.content_browsertests.filter

@@ -8,6 +8,9 @@
 -WebRtcCaptureFromElementBrowserTest.CaptureFromCanvas2DHandlesContextLoss
 -WebRtcCaptureFromElementBrowserTest.CaptureFromOpaqueCanvas2DHandlesContextLoss
 
+# TODO: investigate flaky failure http://crbug.com/783434
+-GpuProcessHostBrowserTest.Shutdown
+
 #### WaitForChildFrameSurfaceReady
 # WaitForChildFrameSurfaceReady doesn't work http://crbug.com/763452
 -PointerLockBrowserTest.*
@@ -84,17 +87,6 @@
 # GL Renderer Check Failure on Mac https://crbug.com/817830
 -WebContentsVideoCaptureDeviceBrowserTestP.CapturesContentChanges/*
 
-#### Unknown Flakes
-# TODO: investigate flaky failure http://crbug.com/783434
--GpuProcessHostBrowserTest.Shutdown
-
-# TODO: investigate flaky failure http://crbug.com/790683
--SitePerProcessBrowserTest.CrossSiteIframeBlockedByXFrameOptionsOrCSP
-
-# TODO: investigate flaky failures http://crbug.com/792739
--SitePerProcessFeaturePolicyBrowserTest.TestFeaturePolicyReplicationFromRemoteFrames
--IsolatedOriginTest.ProcessLimit
--SitePerProcessBrowserTest.RFPHDestruction
-
+#### Hit Testing
 # Flaky Result on Windows-7 http://crbug.com/883463
 -MainThreadEventQueueBrowserTest.MouseMove

testing/buildbot/filters/viz.browser_tests.filter

@@ -98,10 +98,6 @@
 -ThumbnailTest.ShouldContainProperContentIfCapturedOnNavigatingAway
 -ThumbnailTest.ShouldContainProperContentIfCapturedOnTabSwitch
 
-# Unknown Flakes
-# Flaky timeouts. http://crbug.com/807773
--PDFExtensionClipboardTest.*
-
 # Windows timeouts. https://crbug.com/821029
 -ManifestVerifierBrowserTest.*
 -PrefHashBrowserTest*