Add support in Telemetry for other Ozone based targets

Prior to this commit, Telemetry on Linux Desktop was X11 oriented. The changes
introduced here allow other graphics architectures through Ozone as well for
testing, by recognizing a specific extra browser arguments "--ozone-platform".

For example one can use it as following:

./run_benchmark --browser=exact --browser-executable=./out/Release/chrome --extra-browser-args="--ozone-platform=gbm" <benchmark>

BUG=None

Review URL: https://codereview.chromium.org/901143006

Cr-Commit-Position: refs/heads/master@{#317671}

tools/telemetry/telemetry/core/backends/chrome/desktop_browser_finder.py

@@ -124,10 +124,10 @@ def FindAllAvailableBrowsers(finder_options, device):
   if not CanFindAvailableBrowsers():
     return []
 
-  has_display = True
+  has_x11_display = True
   if (sys.platform.startswith('linux') and
       os.getenv('DISPLAY') == None):
-    has_display = False
+    has_x11_display = False
 
   # Look for a browser in the standard chrome build locations.
   if finder_options.chrome_root:
@@ -259,7 +259,12 @@ def FindAllAvailableBrowsers(finder_options, device):
               browser_name, finder_options, app_path,
               None, False, os.path.dirname(app_path)))
 
-  if len(browsers) and not has_display:
+  has_ozone_platform = False
+  for arg in finder_options.browser_options.extra_browser_args:
+    if "--ozone-platform" in arg:
+      has_ozone_platform = True
+
+  if len(browsers) and not has_x11_display and not has_ozone_platform:
     logging.warning(
       'Found (%s), but you do not have a DISPLAY environment set.' %
       ','.join([b.browser_type for b in browsers]))