Add RECORD_AS_MUCH_AS_POSSIBLE mode to TraceOptions.

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

Index: tools/telemetry/telemetry/core/backends/chrome/tracing_backend.py
diff --git a/tools/telemetry/telemetry/core/backends/chrome/tracing_backend.py b/tools/telemetry/telemetry/core/backends/chrome/tracing_backend.py
index d556febe29184d32ba5ace476e3272e38dcf2d40..6563dbbdce81c57267f6515ab33128028b14cff2 100644
--- a/tools/telemetry/telemetry/core/backends/chrome/tracing_backend.py
+++ b/tools/telemetry/telemetry/core/backends/chrome/tracing_backend.py
@@ -136,8 +136,9 @@ class TracingBackend(object):
     self._CheckNotificationSupported()

[nduca, 2014/08/05 22:50:31]

instead of this, land the c+++ changes without any python changes. then
tomorrow, get the branch number from $src/VERSION. then do a telemetry patch
that does the right thing based on the brower_backend.chrome_branch_number.

[nednguyen, 2014/08/05 23:05:40]

Done.

     req = {'method': 'Tracing.start'}
     self._category_filter = CategoryFilter(custom_categories)
+    req['params'] = [{'options': 'record-as-much-as-possible'}]
     if custom_categories:
-      req['params'] = {'categories': custom_categories}
+      req['params'].append({'categories': custom_categories})
     self._inspector_websocket.SyncRequest(req, timeout)
     self._is_tracing_running = True
     return True