[Telemetry] Teach Telemetry to find and run reference builds.

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

Index: tools/telemetry/telemetry/core/backends/chrome/desktop_browser_finder.py
diff --git a/tools/telemetry/telemetry/core/backends/chrome/desktop_browser_finder.py b/tools/telemetry/telemetry/core/backends/chrome/desktop_browser_finder.py
index 87161d035aef00c978dbe0d4af607314328def49..5a5c759a83e686a303d3d7949caeadb37d562c78 100644
--- a/tools/telemetry/telemetry/core/backends/chrome/desktop_browser_finder.py
+++ b/tools/telemetry/telemetry/core/backends/chrome/desktop_browser_finder.py
@@ -95,6 +95,7 @@ def CanFindAvailableBrowsers():
 def FindAllBrowserTypes(_):
   return [
       'exact',
+      'reference',
       'release',
       'release_x64',
       'debug',
@@ -183,12 +184,17 @@ def FindAllAvailableBrowsers(finder_options):
     AddIfFound('content-shell-' + build_type.lower(), build_dir, build_type,
                content_shell_app_name, True)
 
+  reference_build_root = os.path.join(
+     chrome_root, 'chrome', 'tools', 'test', 'reference_build')
+
   # Mac-specific options.
   if sys.platform == 'darwin':
     mac_canary_root = '/Applications/Google Chrome Canary.app/'
     mac_canary = mac_canary_root + 'Contents/MacOS/Google Chrome Canary'
     mac_system_root = '/Applications/Google Chrome.app'
     mac_system = mac_system_root + '/Contents/MacOS/Google Chrome'
+    mac_reference_root = reference_build_root + '/chrome_mac/Google Chrome.app/'
+    mac_reference = mac_reference_root + 'Contents/MacOS/Google Chrome'
     if path.IsExecutable(mac_canary):
       browsers.append(PossibleDesktopBrowser('canary', finder_options,
                                              mac_canary, None, False,
@@ -198,6 +204,10 @@ def FindAllAvailableBrowsers(finder_options):
       browsers.append(PossibleDesktopBrowser('system', finder_options,
                                              mac_system, None, False,
                                              mac_system_root))
+    if path.IsExecutable(mac_reference):
+      browsers.append(PossibleDesktopBrowser('reference', finder_options,
+                                             mac_reference, None, False,
+                                             mac_reference_root))
 
   # Linux specific options.
   if sys.platform.startswith('linux'):
@@ -213,12 +223,19 @@ def FindAllAvailableBrowsers(finder_options):
       browsers.append(PossibleDesktopBrowser('system', finder_options,
                                              'google-chrome', None, False,
                                              '/opt/google/chrome'))
+    linux_reference = os.path.join(reference_build_root, 'chrome_linux',
+                                   'chrome')
+    if path.IsExecutable(linux_reference):
+      browsers.append(PossibleDesktopBrowser('reference', finder_options,
+                                             'chrome', None, False,
+                                             linux_reference))
 
   # Win32-specific options.
   if sys.platform.startswith('win'):
     app_paths = (
         ('system', os.path.join('Google', 'Chrome', 'Application')),
         ('canary', os.path.join('Google', 'Chrome SxS', 'Application')),
+        ('reference', os.path.join(reference_build_root, 'chrome_win')),
     )
 
     for browser_name, app_path in app_paths: