Disable ShelfBackgroundAnimatorTest.FullscreenAppListBackground on CrOS

Bug:878944
Change-Id: I5a802921bc4de918811d011a246b1daa56c9cbfb

TBR=wutao@chromium.org

Change-Id: I5a802921bc4de918811d011a246b1daa56c9cbfb
Reviewed-on: https://chromium-review.googlesource.com/1195933Reviewed-by: Ned Nguyen <nednguyen@google.com>
Commit-Queue: Ned Nguyen <nednguyen@google.com>
Cr-Commit-Position: refs/heads/master@{#587347}

ash/shelf/shelf_background_animator_unittest.cc

@@ -260,8 +260,15 @@ TEST_F(ShelfBackgroundAnimatorTest, SplitViewBackground) {
   EXPECT_EQ(0, observer_.GetItemBackgroundAlpha());
 }
 
+// Crashes on ChromeOS .  http://crbug.com/878944
+#if defined(OS_CHROMEOS)
+#define MAYBE_FullscreenAppListBackground DISABLED_FullscreenAppListBackground
+#else
+#define MAYBE_FullscreenAppListBackground FullscreenAppListBackground
+#endif
+
 // Verify the alpha values for the SHELF_BACKGROUND_APP_LIST state.
-TEST_F(ShelfBackgroundAnimatorTest, FullscreenAppListBackground) {
+TEST_F(ShelfBackgroundAnimatorTest, MAYBE_FullscreenAppListBackground) {
   PaintBackground(SHELF_BACKGROUND_APP_LIST);
 
   EXPECT_EQ(SHELF_BACKGROUND_APP_LIST, animator_->target_background_type());