[telemetry] Add support for requesting memory dumps via DevTools API

tools/telemetry/telemetry/internal/backends/chrome_inspector/devtools_client_backend.py

 # 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 logging
 import re
 import sys
 
 from telemetry.core import exceptions
 from telemetry import decorators
@@ skipping 196 matching lines @@
           "console.timeEnd('" + backend.id + "');" +
           "console.time.toString().indexOf('[native code]') != -1;")
       if not success:
         raise Exception('Page stomped on console.time')
       trace_data_builder.AddEventsTo(
           trace_data_module.TAB_ID_PART, [backend.id])
 
     assert self._tracing_backend
     return self._tracing_backend.StopTracing(trace_data_builder, timeout)
 
+  def DumpMemory(self, timeout=30):
+    """Dumps memory.
+
+    Returns:
+      GUID of the generated dump if successful, None otherwise.
+
+    Raises:
+      TracingTimeoutException: If more than |timeout| seconds has passed
+      since the last time any data is received.
+      TracingUnrecoverableException: If there is a websocket error.
+      TracingUnexpectedResponseException: If the response contains an error
+      or does not contain the expected result.
+    """
+    self._CreateTracingBackendIfNeeded()
+    return self._tracing_backend.DumpMemory(timeout)
+
 
 class _DevToolsContextMapBackend(object):
   def __init__(self, app_backend, devtools_client):
     self._app_backend = app_backend
     self._devtools_client = devtools_client
     self._contexts = None
     self._inspector_backends_dict = {}
 
   @property
   def contexts(self):
@@ skipping 41 matching lines @@
       # If an InspectorBackend is already created for the tab,
       # webSocketDebuggerUrl will be missing, and this is expected.
       context_id = context['id']
       if context_id not in self._inspector_backends_dict:
         if 'webSocketDebuggerUrl' not in context:
           logging.debug('webSocketDebuggerUrl missing, removing %s'
                         % context_id)
           continue
       valid_contexts.append(context)
     self._contexts = valid_contexts