Create DevToolsHttp and basic DevToolsClientBackend.

tools/telemetry/telemetry/core/backends/chrome_inspector/devtools_http.py

Index: tools/telemetry/telemetry/core/backends/chrome_inspector/devtools_http.py
diff --git a/tools/telemetry/telemetry/core/backends/chrome_inspector/devtools_http.py b/tools/telemetry/telemetry/core/backends/chrome_inspector/devtools_http.py
new file mode 100644
index 0000000000000000000000000000000000000000..f5fd8afdb9ef2449ad13925020e6d2d955f77526
--- /dev/null
+++ b/tools/telemetry/telemetry/core/backends/chrome_inspector/devtools_http.py
@@ -0,0 +1,59 @@
+# Copyright 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import contextlib
+import httplib
+import json
+import socket
+import urllib2
+
+
+class DevToolsClientConnectionError(Exception):
+  pass
+
+
+class DevToolsClientUrlError(DevToolsClientConnectionError):
+  pass
+
+
+class DevToolsHttp(object):
+  """A helper class to send and parse DevTools HTTP requests."""
+
+  def __init__(self, devtools_port):
+    self._devtools_port = devtools_port
+
+  def Request(self, path, timeout=30):
+    """
+    Args:
+      path: The DevTools URL path, without the /json/ prefix.
+      timeout: Timeout defaults to 30 seconds.
+
+    Raises:
+      DevToolsClientConnectionError: If the connection fails.
+    """
+    url = 'http://127.0.0.1:%i/json' % self._devtools_port
+    if path:
+      url += '/' + path
+    try:
+      proxy_handler = urllib2.ProxyHandler({})  # Bypass any system proxy.
+      opener = urllib2.build_opener(proxy_handler)
+      with contextlib.closing(opener.open(url, timeout=timeout)) as req:
+        return req.read()
+    except urllib2.URLError as e:
+      raise DevToolsClientUrlError(e)
+    except (socket.error, httplib.BadStatusLine) as e:
+      raise DevToolsClientConnectionError(e)
+
+  def RequestJson(self, path, timeout=30):
+    """Sends a request and parse the response as JSON.
+
+    Args:
+      path: The DevTools URL path, without the /json/ prefix.
+      timeout: Timeout defaults to 30 seconds.
+
+    Raises:
+      DevToolsClientConnectionError: If the connection fails.
+      ValueError: If the response is not a valid JSON.
+    """
+    return json.loads(self.Request(path, timeout))