Revert "Disable two flaky tests on ChromeOS"

This reverts commit fed7475d501d0622e3604313eb93867405cba55f.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> Disable two flaky tests on ChromeOS
> 
> Disable ShelfLayoutManagerTest.FlingUpOnShelfForFullscreenAppList
> Disable WindowSelectorTest.RoundedEdgeMaskVisibility
> 
> Tbr: xiyuan, xdai
> Bug: 864467, 864465
> Change-Id: I77a0dbcddad5176575f0dc5991beb9eef8090167
> Reviewed-on: https://chromium-review.googlesource.com/1140683
> Reviewed-by: Owen Min <zmin@chromium.org>
> Commit-Queue: Owen Min <zmin@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#575707}

TBR=zmin@chromium.org

Change-Id: I2aaceb5588030a1b14edf9b0c1d2da6165cbf8f1
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 864467, 864465
Reviewed-on: https://chromium-review.googlesource.com/1140460
Reviewed-by: CJ DiMeglio <lethalantidote@chromium.org>
Commit-Queue: CJ DiMeglio <lethalantidote@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575865}
diff --git a/ash/shelf/shelf_layout_manager_unittest.cc b/ash/shelf/shelf_layout_manager_unittest.cc
index 967b958..dd85874 100644
--- a/ash/shelf/shelf_layout_manager_unittest.cc
+++ b/ash/shelf/shelf_layout_manager_unittest.cc
@@ -1416,10 +1416,9 @@
   }
 }
 
-// crbug.com/864467
 // If swiping up on shelf ends with fling event, the app list state should
 // depends on the fling velocity.
-TEST_F(ShelfLayoutManagerTest, DISABLED_FlingUpOnShelfForFullscreenAppList) {
+TEST_F(ShelfLayoutManagerTest, FlingUpOnShelfForFullscreenAppList) {
   Shelf* shelf = GetPrimaryShelf();
   EXPECT_EQ(SHELF_ALIGNMENT_BOTTOM, shelf->alignment());
   EXPECT_EQ(SHELF_AUTO_HIDE_BEHAVIOR_NEVER, shelf->auto_hide_behavior());
diff --git a/ash/wm/overview/window_selector_unittest.cc b/ash/wm/overview/window_selector_unittest.cc
index 2d76ed8..c3286a6 100644
--- a/ash/wm/overview/window_selector_unittest.cc
+++ b/ash/wm/overview/window_selector_unittest.cc
@@ -2801,10 +2801,9 @@
   ToggleOverview();
 }
 
-// crbug.com/864465
 // Verify that the mask that is applied to add rounded corners in overview mode
 // is removed during animations and drags.
-TEST_F(WindowSelectorTest, DISABLED_RoundedEdgeMaskVisibility) {
+TEST_F(WindowSelectorTest, RoundedEdgeMaskVisibility) {
   UpdateDisplay("400x400");
   const gfx::Rect bounds(0, 0, 200, 200);
   std::unique_ptr<aura::Window> window1(CreateWindow(bounds));