Add --serial mode to dm, runs unit tests serially

infra/bots/recipes/swarm_test.py

Index: infra/bots/recipes/swarm_test.py
diff --git a/infra/bots/recipes/swarm_test.py b/infra/bots/recipes/swarm_test.py
index 5b9d993f2e6733ae10008b862c9eb2ab2f42db37..b2074a3c614b77bbcae5f33cf710251eb0589454 100644
--- a/infra/bots/recipes/swarm_test.py
+++ b/infra/bots/recipes/swarm_test.py
@@ -307,6 +307,7 @@ def dm_flags(bot):
 
   if 'NexusPlayer' in bot:
     match.append('~ResourceCache')
+    match.append('~ColorSpaceCRBug')

[mtklein, 2016/08/16 23:54:06]

Is this still going to be necessary once we've made the test run in complete
isolation?  I don't suppose we can construct a smaller test case?

[msarett, 2016/08/17 12:40:45]

I'll run the trybot, but I think we'll still need it.

Unforuntately, the bug only reproduces if we have 3 giant gamma tables - large
enough to overflow uint32_t when their sizes are added together.  And if the ICC
profile isn't large enough to contain the tables, we reject it early.  So we
need a really large ICC profile.

[mtklein, 2016/08/17 12:45:12]

So you're saying it allocates 2 giant tables, then the third tips it over?

Can we write the parsing to check the sizes of all its allocations first before
doing any?

[msarett, 2016/08/17 12:51:47]

This is actually what we do - the large memory use is from the decompressed ICC
profile.  We allocate gammas in one block of memory - so we haven't allocated
anything yet.  The bug fix prevents us from trying to allocate if we overflow
when adding sizeof(gamma1) + sizeof(gamma2) + sizeof(gamma3).

FWIW, I intend to write another CL that rejects all tables that are greater than
<some large number of entries>.  That may incidentally also fix this bug, but I
think the overflow checks are important on their own.

 
   if 'Nexus10' in bot: # skia:5509
     match.append('~CopySurface')
@@ -320,6 +321,10 @@ def dm_flags(bot):
   if 'TSAN' in bot:
     match.extend(['~ReadWriteAlpha'])   # Flaky on TSAN-covered on nvidia bots.
 
+  # For memory intensive tests that we don't want to run multi-threaded.
+  serial = []
+  serial.append('ColorSpaceCRBug')
+
   if blacklist:
     args.append('--blacklist')
     args.extend(blacklist)
@@ -328,6 +333,10 @@ def dm_flags(bot):
     args.append('--match')
     args.extend(match)
 
+  if serial:
+    args.append('--serial')
+    args.extend(serial)
+
   # These bots run out of memory running RAW codec tests. Do not run them in
   # parallel
   if ('NexusPlayer' in bot or 'Nexus5' in bot or 'Nexus9' in bot