Make it harder to get ContentSettingsType histogram values wrong

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 cc911dcc02deacec03a75fb2d3e49255db13514b..a825ea80e313c59d746331de2a6097d8bf568ebf 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -8510,6 +8510,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
     Count of how often a specific content type has a content settings exception
     defined for a file: scheme with no path (i.e., wildcard path). Recorded once
     per exception at browser start.
+
+    Note: The values of this metric collected for Chrome 49 (early 2016) are
+    innacurate and should not be trusted. crbug.com/589255.
   </summary>
 </histogram>
 
@@ -8520,6 +8523,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
     Count of how often a specific content type has a content settings exception
     defined for a file: scheme with a valid, non-empty path. Recorded once per
     exception at browser start.
+
+    Note: The values of this metric collected for Chrome 49 (early 2016) are
+    innacurate and should not be trusted. crbug.com/589255.
   </summary>
 </histogram>
 
@@ -81093,6 +81099,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>
     Count of how often a specific content type (permission) is changed using the
     content settings menu.
+
+    Note: The values of this metric collected for Chrome 49 (early 2016) are
+    innacurate and should not be trusted. crbug.com/589255.
   </summary>
 </histogram>
 
@@ -81103,6 +81112,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>
     Count of how often a specific content type (permission) is set to 'Allowed'
     using the content settings menu.
+
+    Note: The values of this metric collected for Chrome 49 (early 2016) are
+    innacurate and should not be trusted. crbug.com/589255.
   </summary>
 </histogram>
 
@@ -81113,6 +81125,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>
     Count of how often a specific content type (permission) is set to 'Blocked'
     using the content settings menu.
+
+    Note: The values of this metric collected for Chrome 49 (early 2016) are
+    innacurate and should not be trusted. crbug.com/589255.
   </summary>
 </histogram>
 
@@ -81123,6 +81138,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>
     Count of how often a specific content type (permission) is reset to the
     default value using the content settings menu.
+
+    Note: The values of this metric collected for Chrome 49 (early 2016) are
+    innacurate and should not be trusted. crbug.com/589255.
   </summary>
 </histogram>
 
@@ -81133,6 +81151,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>
     Count of how often a specific content type (permission) is changed using the
     Origin Info dialog.
+
+    Note: The values of this metric collected for Chrome 49 (early 2016) are
+    innacurate and should not be trusted. crbug.com/589255.
   </summary>
 </histogram>
 
@@ -81143,6 +81164,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>
     Count of how often a specific content type (permission) is set to 'Allowed'
     using the Origin Info dialog.
+
+    Note: The values of this metric collected for Chrome 49 (early 2016) are
+    innacurate and should not be trusted. crbug.com/589255.
   </summary>
 </histogram>
 
@@ -81153,6 +81177,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>
     Count of how often a specific content type (permission) is set to 'Blocked'
     using the Origin Info dialog.
+
+    Note: The values of this metric collected for Chrome 49 (early 2016) are
+    innacurate and should not be trusted. crbug.com/589255.
   </summary>
 </histogram>
 
@@ -81166,6 +81193,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>
     Count of how often a specific content type (permission) is changed using the
     Page Info UI.
+
+    Note: The values of this metric collected for Chrome 49 (early 2016) are
+    innacurate and should not be trusted. crbug.com/589255.
   </summary>
 </histogram>
 
@@ -86926,8 +86956,13 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="22" label="App banner setting (Android only)"/>
   <int value="23" label="Site engagement setting"/>
   <int value="24" label="Durable storage setting"/>
-  <int value="25" label="Key generation setting"/>
-  <int value="26" label="Background sync setting"/>
+  <int value="25" label="Key generation setting [removed]"/>
+  <int value="26" label="Bluetooth guard setting"/>
+  <int value="27" label="Background sync setting"/>
+  <int value="28" label="Autoplay setting"/>
+  <int value="30" label="Important site info setting"/>
+  <int value="31" label="Permission autoblocker data setting"/>
+  <int value="32" label="Subresource filter setting"/>
 </enum>
 
 <enum name="ContentTypeParseableResult" type="int">