Skip ElfCoreDumpTest.ValidCoreFile test if no core dump is generated.

CrashGenerator::CreateChildCrash() may have some flakiness. This patch
changes ElfCoreDumpTest to temporarily skip the ValidCoreFile test if
no core dump is generated by CrashGenerator::CreateChildCrash(), but
print out the error message to help debug the flakiness.

BUG=chromium-os:24982
TEST=Tested the following:
1. Build on 32-bit and 64-bit Linux with gcc 4.6.
2. All unit tests pass.
Review URL: http://breakpad.appspot.com/342001

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@904 4c0a9323-5329-0410-9bdc-e9ce6186880e
2 files changed