Bug 1509175 - MnH has to use a resolution of 1600x1200 instead of 1366x768 for virtual screen. r=ato

Differential Revision: https://phabricator.services.mozilla.com/D12626

--HG--
extra : moz-landing-system : lando

testing/mozharness/scripts/marionette.py

@@ -96,6 +96,20 @@ class MarionetteTest(TestingMixin, MercurialScript, TransferMixin,
          "default": False,
          "help": "Run tests in headless mode.",
          }
+    ], [
+        ["--headless-width"],
+        {"action": "store",
+         "dest": "headless_width",
+         "default": "1600",
+         "help": "Specify headless virtual screen width (default: 1600).",
+         }
+    ], [
+        ["--headless-height"],
+        {"action": "store",
+         "dest": "headless_height",
+         "default": "1200",
+         "help": "Specify headless virtual screen height (default: 1200).",
+         }
     ], [
        ["--allow-software-gl-layers"],
        {"action": "store_true",
@@ -291,9 +305,6 @@ class MarionetteTest(TestingMixin, MercurialScript, TransferMixin,
         if not self.config['e10s']:
             cmd.append('--disable-e10s')
 
-        if self.config['headless']:
-            cmd.append('--headless')
-
         cmd.append('--gecko-log=-')
 
         if self.config.get("structured_output"):
@@ -330,6 +341,11 @@ class MarionetteTest(TestingMixin, MercurialScript, TransferMixin,
             env['MOZ_WEBRENDER'] = '1'
             env['MOZ_ACCELERATED'] = '1'
 
+        if self.config['headless']:
+            env['MOZ_HEADLESS'] = '1'
+            env['MOZ_HEADLESS_WIDTH'] = self.config['headless_width']
+            env['MOZ_HEADLESS_HEIGHT'] = self.config['headless_height']
+
         if not os.path.isdir(env['MOZ_UPLOAD_DIR']):
             self.mkdir_p(env['MOZ_UPLOAD_DIR'])
         env = self.query_env(partial_env=env)

testing/mozharness/scripts/web_platform_tests.py

@@ -76,13 +76,13 @@ class WebPlatformTest(TestingMixin, MercurialScript, CodeCoverageMixin, AndroidM
             "action": "store",
             "dest": "headless_width",
             "default": "1600",
-            "help": "Specify headless fake screen width (default: 1600)."}
+            "help": "Specify headless virtual screen width (default: 1600)."}
          ],
         [["--headless-height"], {
             "action": "store",
             "dest": "headless_height",
             "default": "1200",
-            "help": "Specify headless fake screen height (default: 1200)."}
+            "help": "Specify headless virtual screen height (default: 1200)."}
          ],
         [["--single-stylo-traversal"], {
             "action": "store_true",