Change the new-task-manager flag so that the new implementation is enabled by default for all users.

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 1caf2b88d7866583f25d8894835f45bd8bf48cf5..f1197212fd6ca02f2cf432ea1ac18c6944ccd3c9 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -62202,7 +62202,6 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="-2077268643" label="disable-device-enumeration"/>
   <int value="-2075725205" label="disable-new-zip-unpacker"/>
   <int value="-2067166422" label="enable-slimming-paint-v2"/>
-  <int value="-2063352474" label="enable-new-task-manager"/>

[Lei Zhang, 2015/08/14 18:17:47]

I think you are suppose to never delete?

[Alexei Svitkine (slow), 2015/08/14 18:27:51]

Correct. Please keep the old entry so that old data can be decoded.

[afakhry, 2015/08/14 18:36:04]

I should keep the old entry even though the old flag has been removed entirely?
Do we remove it at a later point in time?

[afakhry, 2015/08/14 18:57:09]

Done.

   <int value="-2063014275" label="enable-web-bluetooth"/>
   <int value="-2047822258" label="enable-avfoundation"/>
   <int value="-2025367104" label="enable-material-design-ntp"/>
@@ -62588,6 +62587,7 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="1272699563" label="enable-hosted-mode"/>
   <int value="1279584261" label="enable-carrier-switching"/>
   <int value="1283960113" label="disable-fixed-position-compositing"/>
+  <int value="1298981651" label="disable-new-task-manager"/>
   <int value="1319725131" label="enable-distance-field-text"/>
   <int value="1320201920" label="enable-touchpad-three-finger-click"/>
   <int value="1351830811" label="do-not-ignore-autocomplete-off"/>