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/1140683Reviewed-by: Owen Min <zmin@chromium.org>
Commit-Queue: Owen Min <zmin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575707}

ash/shelf/shelf_layout_manager_unittest.cc

@@ -1416,9 +1416,10 @@ TEST_F(ShelfLayoutManagerTest, GestureDrag) {
   }
 }
 
+// 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, FlingUpOnShelfForFullscreenAppList) {
+TEST_F(ShelfLayoutManagerTest, DISABLED_FlingUpOnShelfForFullscreenAppList) {
   Shelf* shelf = GetPrimaryShelf();
   EXPECT_EQ(SHELF_ALIGNMENT_BOTTOM, shelf->alignment());
   EXPECT_EQ(SHELF_AUTO_HIDE_BEHAVIOR_NEVER, shelf->auto_hide_behavior());

ash/wm/overview/window_selector_unittest.cc

@@ -2801,9 +2801,10 @@ TEST_F(WindowSelectorTest, Backdrop) {
   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, RoundedEdgeMaskVisibility) {
+TEST_F(WindowSelectorTest, DISABLED_RoundedEdgeMaskVisibility) {
   UpdateDisplay("400x400");
   const gfx::Rect bounds(0, 0, 200, 200);
   std::unique_ptr<aura::Window> window1(CreateWindow(bounds));