Slightly tweak the tools/heapcheck/chrome_tests.py script to read less gtest filter files

tools/heapcheck/suppressions.txt

 # There are three kinds of suppressions in this file.
 # 1. third party stuff we have no control over
 #
 # 2. intentional unit test errors, or stuff that is somehow a false positive
 # in our own code, or stuff that is so trivial it's not worth fixing
 #
 # 3. Suppressions for real chromium bugs that are not yet fixed.
 # These should all be in chromium's bug tracking system (but a few aren't yet).
 # Periodically we should sweep this file and the bug tracker clean by
 # running overnight and removing outdated bugs/suppressions.
@@ skipping 1728 matching lines @@
    ...
    fun:MockDownloadManager*
    fun:DownloadManagerTest*
    fun:DownloadManagerTest_*
 }
 {
    bug_93006d
    Heapcheck:Leak
    ...
    fun:DownloadManager::AddObserver
-   fun:::SelectFileObserver::SelectFileObserver
+   fun:*SelectFileObserver
    fun:DownloadManagerTest_*
 }