Add source column to chrome://policy showing the origins of policies.

components/policy_strings.grdp

Index: components/policy_strings.grdp
diff --git a/components/policy_strings.grdp b/components/policy_strings.grdp
index 8433599b2dd453c700591272c9638f2f058fd9d4..d38ff42133926bb6c297aacc5796c53d2675b03e 100644
--- a/components/policy_strings.grdp
+++ b/components/policy_strings.grdp
@@ -291,6 +291,9 @@
   <message name="IDS_POLICY_HEADER_STATUS" desc="Table header for the column in policy table that contains the policy status.">
     Status
   </message>
+  <message name="IDS_POLICY_HEADER_SOURCE" desc="Table header for the column in policy table that contains the policy source.">
+    Source
+  </message>
   <message name="IDS_POLICY_SHOW_EXPANDED_VALUE" desc="Text for the link that shows the policy value. Used when the policy value is too long to be always visible.">
     Show value
   </message>
@@ -319,4 +322,16 @@
   <message name="IDS_POLICY_INVALID_BOOKMARK" desc="Text displayed in the status column when an entry of the ManagedBookmarks policy is not a valid bookmark.">
     Ignored invalid bookmark at index <ph name="ENTRY_INDEX">$1<ex>3</ex></ph>
   </message>
+  <message name="IDS_POLICY_SOURCE_ENTERPRISE_DEFAULT" desc="Indicates that a policy is set by default in an enterprise environment (for Chrome OS only).">
+    Enterprise Default
+  </message>
+  <message name="IDS_POLICY_SOURCE_CLOUD" desc="Indicates that the policy originates from the cloud.">
+    Cloud
+  </message>
+  <message name="IDS_POLICY_SOURCE_PLATFORM" desc="Indicates that the policy is obtained from the local OS.">
+    Platform
+  </message>
+  <message name="IDS_POLICY_SOURCE_BUILT_IN" desc="Indicates that the policy is programmatically set (e.g. to enforce ash tray visibility in public sessions).">
+    Built-In
+  </message>
 </grit-part>