Make MB aware of iOS bot configs and get iOS working.

tools/mb/mb_config.pyl

Index: tools/mb/mb_config.pyl
diff --git a/tools/mb/mb_config.pyl b/tools/mb/mb_config.pyl
index 259a016184320a22aa8da685820fcaddc6925a05..3b5b99dd3dd7b6190f48fd76314066918c3899f2 100644
--- a/tools/mb/mb_config.pyl
+++ b/tools/mb/mb_config.pyl
@@ -65,6 +65,8 @@
     'noswarming_gyp_release_bot_mac_strip': ['noswarming', 'gyp', 'release_bot', 'mac_strip'],
     'noswarming_gyp_release_bot_x86_linux_dump_symbols': ['noswarming', 'gyp', 'release_bot', 'x86', 'linux_dump_symbols'],
 
+    'passthrough': ['passthrough'],
+
     'swarming_asan_lsan_gyp_release_trybot': ['swarming', 'asan', 'lsan', 'release_trybot'],
     'swarming_msan_gyp_release_trybot': ['swarming', 'chromeos', 'msan', 'gyp', 'release_trybot'],
     'swarming_deterministic_gyp_release_bot': ['swarming', 'deterministic', 'gyp', 'release_bot'],
@@ -292,6 +294,16 @@
       'gyp_defines': 'branding=Chrome buildtype=Official',
     },
 
+    # If this config is used, this means we will use the values for
+    # type, gn_args, gyp_defines, and gyp_crosscompile from the environment
+    # variables MB_TYPE, GN_ARGS, GYP_DEFINES, and GYP_CROSSCOMPILE 
+    # respectively. We do this in order to avoid having to configure bots
+    # in two different src-side places. At the moment this must only be
+    # used on the iOS bots.
+    'passthrough': {
+      'type': 'passthrough',
+    },
+
     'release': {
       'gn_args': 'is_debug=false',
     },
@@ -395,6 +407,8 @@
       'Cast Android (dbg)': 'android_cast_gyp_debug_static_bot',
     },
     'chromium.mac': {
+      'iOS Device GN': 'passthrough',
+      'iOS Simulator GN (dbg)': 'passthrough',

[smut, 2015/11/10 22:08:37]

But you still need to enter every GN bot here, in addition to master.cfg,
slaves.cfg, and the bot-specific .json.

Can MB be changed so there's a way to invoke it in --passthrough mode, rather
than having it consult mb_config.pyl and find out it should be in passthrough
mode?

Alternately, can it be set up so any bot that has no entry here defaults to
passthrough mode?

[Dirk Pranke, 2015/11/10 22:46:06]

MB can't do either of those things the code exists in this patch.

One could of course modify the code to do either of these things.

I am reluctant to do so because I'm using mb_config.pyl as the source of truth
for the GYP->GN migration, and if I don't list bots here then it will not be
obvious whether or not they've been even looked at in the context of the
migration.

Of course, adding passthrough at all partially defeats my intentions.

Can we let this go as-is for the moment and revisit this in a subsequent patch
while I think about it some more?

[smut, 2015/11/10 23:30:00]

Agreed that MB can't do these things, but I'm asking for it to be able to.

I hesitate to let this go, because it might end up just staying like this for
awhile, and this makes it even more annoying to add a new bot since it now has
to be enumerated here too. But, iOS upstream bots are added so rarely that I
guess it's ok.

       'Mac GN': 'gn_release_bot',
       'Mac GN (dbg)': 'gn_debug_static_bot',
     },
@@ -499,6 +513,8 @@
       'linux_ecs_ozone': 'embedded_gyp_debug_bot',
     },
     'tryserver.chromium.mac': {
+      'ios_dbg_simulator_gn': 'passthrough',
+      'ios_rel_device_gn': 'passthrough',
       'mac_chromium_gn_dbg': 'gn_debug_static_bot',
       'mac_chromium_gn_rel': 'gn_release_trybot',
       'mac_chromium_gn_upload': 'gn_release_bot',