Remove text from EXPECT_DEATH for clipboard test

On ChromeOS the text does not appear in the output, so we should just
pass "" like other EXPECT_DEATH calls do.

  Result: died but not with expected error.
  Expected: contains regular expression "Check failed"
  Actual msg:
  [  DEATH   ]
  Stack trace:
  #0 0x5577cb1ef7ee ui::(anonymous namespace)::ClipboardTest_Bitmap_F16_Premul_Test<>::TestBody()

R=sky@chromium.org

Bug: 1144462
Change-Id: I8890b6fe3e5bfacf49c8bbb840a21543502ea537
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2530797Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: danakj <danakj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825984}

ui/base/clipboard/clipboard_test_template.h

@@ -541,7 +541,7 @@ TYPED_TEST(ClipboardTest, Bitmap_F16_Premul) {
                                SkImageInfo::Make(1, 1, kRGBA_F16_SkColorType,
                                                  kPremul_SkAlphaType),
                                &kRGBAF16Premul, &kRGBAPremul),
-               "Check failed");
+               "");
 }
 
 TYPED_TEST(ClipboardTest, Bitmap_N32_Premul) {