[Telemetry] Resolve errors due to new pylint checker.

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

Index: tools/telemetry/telemetry/core/backends/chrome/ios_browser_finder.py
diff --git a/tools/telemetry/telemetry/core/backends/chrome/ios_browser_finder.py b/tools/telemetry/telemetry/core/backends/chrome/ios_browser_finder.py
index f65f09bf81619be7b67d579a1e9193c2e4192545..327f2afde82a17ce08f399ff525c6cbf3ebe3a13 100644
--- a/tools/telemetry/telemetry/core/backends/chrome/ios_browser_finder.py
+++ b/tools/telemetry/telemetry/core/backends/chrome/ios_browser_finder.py
@@ -70,7 +70,7 @@ def FindAllBrowserTypes(_):
 def _IsIosDeviceAttached():
   devices = subprocess.check_output('system_profiler SPUSBDataType', shell=True)
   for line in devices.split('\n'):
-    if line and re.match('\s*(iPod|iPhone|iPad):', line):
+    if line and re.match(r'\s*(iPod|iPhone|iPad):', line):
       return True
   return False
 
@@ -86,8 +86,8 @@ def FindAllAvailableBrowsers(finder_options):
   options = finder_options.browser_options
 
   options.browser_type = 'ios-chrome'
-  backend = ios_browser_backend.IosBrowserBackend(options)
   host = platform.GetHostPlatform()
+  backend = ios_browser_backend.IosBrowserBackend(host, options)
   # TODO(baxley): Use idevice to wake up device or log debug statement.
   if not host.IsApplicationRunning(IOS_WEBKIT_DEBUG_PROXY):
     host.LaunchApplication(IOS_WEBKIT_DEBUG_PROXY)
@@ -103,11 +103,11 @@ def FindAllAvailableBrowsers(finder_options):
   debug_urls = backend.GetWebSocketDebuggerUrls(device_urls)
 
   # Get the userAgent for each UIWebView to find the browsers.
-  browser_pattern = ('\)\s(%s)\/(\d+[\.\d]*)\sMobile'
+  browser_pattern = (r'\)\s(%s)\/(\d+[\.\d]*)\sMobile'
                      % '|'.join(IOS_BROWSERS.keys()))
   browser_types = set()
   for url in debug_urls:
-    context = {'webSocketDebuggerUrl':url , 'id':1}
+    context = {'webSocketDebuggerUrl': url, 'id': 1}
     inspector = inspector_backend.InspectorBackend(backend, context)
     res = inspector.EvaluateJavaScript("navigator.userAgent")
     match_browsers = re.search(browser_pattern, res)