Remove obsolete mac_gpu

BUG=chromium:426897
R=kbr@google.com,phajdan@google.com,reed@google.com

NOTREECHECKS=true

Review URL: https://codereview.chromium.org/812963003
diff --git a/tools/roll_deps.py b/tools/roll_deps.py
index e255099..84f634d 100755
--- a/tools/roll_deps.py
+++ b/tools/roll_deps.py
@@ -52,7 +52,6 @@
   'linux_layout_rel',
   'mac',
   'mac_asan',
-  'mac_gpu',
   'mac_layout',
   'mac_layout_rel',
   'win',
diff --git a/trybots_to_run/chrome/depsroll b/trybots_to_run/chrome/depsroll
index bd3757d..d51e1e1 100644
--- a/trybots_to_run/chrome/depsroll
+++ b/trybots_to_run/chrome/depsroll
@@ -1 +1 @@
-android,cros_daisy,linux,linux_asan,linux_chromeos,linux_chromeos_asan,linux_gpu,linux_heapcheck,linux_layout,linux_layout_rel,mac,mac_asan,mac_gpu,mac_layout,mac_layout_rel,win,win_gpu,win_layout,win_layout_rel
\ No newline at end of file
+android,cros_daisy,linux,linux_asan,linux_chromeos,linux_chromeos_asan,linux_gpu,linux_heapcheck,linux_layout,linux_layout_rel,mac,mac_asan,mac_layout,mac_layout_rel,win,win_gpu,win_layout,win_layout_rel
diff --git a/trybots_to_run/chrome/layout b/trybots_to_run/chrome/layout
index 29afb80..51cd925 100644
--- a/trybots_to_run/chrome/layout
+++ b/trybots_to_run/chrome/layout
@@ -1 +1 @@
-linux_gpu,linux_layout,linux_layout_rel,mac_gpu,mac_layout,mac_layout_rel,win_gpu,win_layout,win_layout_rel
\ No newline at end of file
+linux_gpu,linux_layout,linux_layout_rel,mac_layout,mac_layout_rel,win_gpu,win_layout,win_layout_rel