[BrowserSwitcher] Update histogram expiry date

All the histograms are set to expire in 1 year. Since most histograms
didn't have an expiry date yet, this CL also adds one.

Bug: 975169
Change-Id: I6294b0c47795a96d3f131e94f1151c689d01480a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1664513Reviewed-by: Brian White <bcwhite@chromium.org>
Commit-Queue: Nicolas Ouellet-Payeur <nicolaso@chromium.org>
Cr-Commit-Position: refs/heads/master@{#670107}

tools/metrics/histograms/histograms.xml

@@ -15742,7 +15742,8 @@ uploading your change for review.
   </summary>
 </histogram>
 
-<histogram name="BrowserSwitcher.CacheFile.MkDirSuccess" enum="BooleanSuccess">
+<histogram name="BrowserSwitcher.CacheFile.MkDirSuccess" enum="BooleanSuccess"
+    expires_after="2020-06-18">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -15751,7 +15752,8 @@ uploading your change for review.
   </summary>
 </histogram>
 
-<histogram name="BrowserSwitcher.CacheFile.MkTempSuccess" enum="BooleanSuccess">
+<histogram name="BrowserSwitcher.CacheFile.MkTempSuccess" enum="BooleanSuccess"
+    expires_after="2020-06-18">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -15761,7 +15763,8 @@ uploading your change for review.
   </summary>
 </histogram>
 
-<histogram name="BrowserSwitcher.CacheFile.MoveSuccess" enum="BooleanSuccess">
+<histogram name="BrowserSwitcher.CacheFile.MoveSuccess" enum="BooleanSuccess"
+    expires_after="2020-06-18">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -15772,7 +15775,8 @@ uploading your change for review.
   </summary>
 </histogram>
 
-<histogram name="BrowserSwitcher.Decision" enum="BooleanBrowserSwitch">
+<histogram name="BrowserSwitcher.Decision" enum="BooleanBrowserSwitch"
+    expires_after="2020-06-18">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -15784,7 +15788,7 @@ uploading your change for review.
 </histogram>
 
 <histogram name="BrowserSwitcher.ExternalGreylistSize" units="rules"
-    expires_after="M79">
+    expires_after="2020-06-18">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -15793,7 +15797,8 @@ uploading your change for review.
   </summary>
 </histogram>
 
-<histogram name="BrowserSwitcher.ExternalSitelistSize" units="rules">
+<histogram name="BrowserSwitcher.ExternalSitelistSize" units="rules"
+    expires_after="2020-06-18">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -15802,7 +15807,8 @@ uploading your change for review.
   </summary>
 </histogram>
 
-<histogram name="BrowserSwitcher.GreylistSize" units="rules">
+<histogram name="BrowserSwitcher.GreylistSize" units="rules"
+    expires_after="2020-06-18">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -15811,7 +15817,8 @@ uploading your change for review.
   </summary>
 </histogram>
 
-<histogram name="BrowserSwitcher.GreylistWildcard" enum="BooleanPresent">
+<histogram name="BrowserSwitcher.GreylistWildcard" enum="BooleanPresent"
+    expires_after="2020-06-18">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -15821,7 +15828,8 @@ uploading your change for review.
   </summary>
 </histogram>
 
-<histogram name="BrowserSwitcher.IeemSitelistSize" units="rules">
+<histogram name="BrowserSwitcher.IeemSitelistSize" units="rules"
+    expires_after="2020-06-18">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -15830,7 +15838,8 @@ uploading your change for review.
   </summary>
 </histogram>
 
-<histogram name="BrowserSwitcher.LaunchSuccess" enum="BooleanSuccess">
+<histogram name="BrowserSwitcher.LaunchSuccess" enum="BooleanSuccess"
+    expires_after="2020-06-18">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -15839,7 +15848,8 @@ uploading your change for review.
   </summary>
 </histogram>
 
-<histogram name="BrowserSwitcher.UrlListSize" units="rules">
+<histogram name="BrowserSwitcher.UrlListSize" units="rules"
+    expires_after="2020-06-18">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -15849,7 +15859,7 @@ uploading your change for review.
 </histogram>
 
 <histogram name="BrowserSwitcher.UrlListWildcard" enum="BooleanPresent"
-    expires_after="M77">
+    expires_after="2020-06-18">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>