Switch startTracing to use record-as-much-as-possible option.

tools/telemetry/telemetry/core/platform/tracing_options.py

Index: tools/telemetry/telemetry/core/platform/tracing_options.py
diff --git a/tools/telemetry/telemetry/core/platform/tracing_options.py b/tools/telemetry/telemetry/core/platform/tracing_options.py
index f2d747718bde5da4bc8264fad26e9cb05007642c..336ea3523f1b992683f11d50419dd05bd7e67924 100644
--- a/tools/telemetry/telemetry/core/platform/tracing_options.py
+++ b/tools/telemetry/telemetry/core/platform/tracing_options.py
@@ -2,12 +2,35 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+RECORD_AS_MUCH_AS_POSSIBLE = 'record-as-much-as-possible'
+RECORD_UNTIL_FULL = 'record-until-full'
+RECORD_MODES = (RECORD_AS_MUCH_AS_POSSIBLE, RECORD_UNTIL_FULL)
+
+
 class TracingOptions(object):
   """Tracing options control which core tracing systems should be enabled.
 
   This simply turns on those systems. If those systems have additional options,
   e.g. what to trace, then they are typically configured by adding
   categories to the TracingCategoryFilter.
+
+  Options:
+         enable_chrome_trace: a boolean that specifies whether to enable
+                            chrome tracing.
+         record_mode: can be any mode in RECORD_MODES. This corresponds to
+                    record modes in chrome (see
+                    TraceRecordMode in base/debug/trace_event_impl.h for more
+                    information)
   """
   def __init__(self):
-    self.enable_chrome_trace = False
+    self.enable_chrome_trace = False
+    self._record_mode = RECORD_AS_MUCH_AS_POSSIBLE
+
+  @property
+  def record_mode(self):  # pylint: disable=E0202
+    return self._record_mode
+
+  @record_mode.setter
+  def record_mode(self, value):  # pylint: disable=E0202
+    assert value in RECORD_MODES
+    self._record_mode = value