Remove suppressions as tests now pass.

TESTED=Build valgrind on Linux/Mac, tests pass 100/100 times.
BUG=159234,227278,222532

Review URL: https://codereview.chromium.org/647103002

Cr-Commit-Position: refs/heads/master@{#299194}

tools/valgrind/gtest_exclude/content_unittests.gtest.txt

-# Flaky, see http://crbug.com/227278
-WebContentsVideoCaptureDeviceTest.WebContentsDestroyed
-
 # False positive, according to crbug.com/386080
 WebLayerImplFixedBoundsTest.CompareToWebLayerImplComplex
 WebLayerImplFixedBoundsTest.CompareToWebLayerImplSimple

tools/valgrind/gtest_exclude/content_unittests.gtest_mac.txt

@@ -13,13 +13,8 @@ MacSandboxTest.ClipboardAccess
 # mach_override assertion, see http://crbug.com/162728
 BlobURLRequestJobTest.*
 
-# Fail, see http://crbug.com/159234
-WebContentsVideoCaptureDeviceTest.GoesThroughAllTheMotions
-WebContentsVideoCaptureDeviceTest.BadFramesGoodFrames
-
 # Hang at arbitrary point, can't tell where exactly, see http://crbug.com/163314
 RenderWidgetHostViewMacTest.*
-WebContentsVideoCaptureDeviceTest.*
 RenderViewHostTest.*
 DeviceMotionEventPumpTest.*