Move timeline and importers to use telemetry.value.TraceValue

tools/telemetry/telemetry/core/platform/tracing_controller_backend.py

Index: tools/telemetry/telemetry/core/platform/tracing_controller_backend.py
diff --git a/tools/telemetry/telemetry/core/platform/tracing_controller_backend.py b/tools/telemetry/telemetry/core/platform/tracing_controller_backend.py
index fe7849f85713258fcb783a00a52f384c14dadfcb..b0e26522ad302c8007bb8dd2cc078b6f2107a30f 100644
--- a/tools/telemetry/telemetry/core/platform/tracing_controller_backend.py
+++ b/tools/telemetry/telemetry/core/platform/tracing_controller_backend.py
@@ -4,7 +4,7 @@
 
 from telemetry.core.platform import tracing_category_filter
 from telemetry.core.platform import tracing_options
-
+from telemetry.value import trace as trace_value_module
 
 class TracingControllerBackend(object):
   def __init__(self, platform_backend):
@@ -47,14 +47,14 @@ class TracingControllerBackend(object):
     if len(self.running_browser_backends) != 1:
       raise NotImplementedError()
 
-    result = None
+    builder = trace_value_module.TraceValueBuilder()
     if self._current_trace_options.enable_chrome_trace:
       browser_backend = self.running_browser_backends[0]
-      result = browser_backend.StopTracing()
+      result = browser_backend.StopTracing(builder)
 
     self._current_trace_options = None
     self._current_category_filter = None
-    return result
+    return builder.AsValue()
 
   def IsChromeTracingSupported(self, browser):
     browser_backend = self._platform_backend.GetBackendForBrowser(browser)