[MemSheriff] Disable ICOImageDecoderTest.Decoding.

Fails on a subset of bots.

BUG=371290
TBR=piman@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/879303003

Cr-Commit-Position: refs/heads/master@{#313509}

content/renderer/ico_image_decoder_unittest.cc

@@ -18,7 +18,8 @@ class ICOImageDecoderTest : public ImageDecoderTest {
   }
 };
 
-TEST_F(ICOImageDecoderTest, Decoding) {
+// http://crbug.com/371290
+TEST_F(ICOImageDecoderTest, DISABLED_Decoding) {
   TestDecoding();
 }