Fix web accessible resource checks in ShouldAllowOpenURL

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 93ea14f12ed4a018cc65c2f10994b2c3a7290c46..568fb7197776a93f4a68515b5461e8017ddd246a 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -17509,6 +17509,17 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Extensions.ShouldAllowOpenURL.Failure"
+    enum="ShouldAllowOpenURLFailureReason">
+  <owner>alexmos@chromium.org</owner>
+  <summary>
+    When the web-accessible resource check in
+    ChromeContentBrowserClientExtensionsPart::ShouldAllowOpenURL fails, this
+    records the reason for the failure.  This check is performed on navigations
+    that utilize the OpenURL path as well as on transfers.
+  </summary>
+</histogram>
+
 <histogram name="Extensions.StartupDelay" units="ms">
   <owner>asargent@chromium.org</owner>
   <summary>The time one extension delays network requests at startup.</summary>
@@ -99105,6 +99116,19 @@ value.
   <int value="1" label="Failure"/>
 </enum>
 
+<enum name="ShouldAllowOpenURLFailureReason" type="int">
+  <summary>
+    Specifies the reason why the web-accessible resource check in
+    ShouldAllowOpenURL fails.
+  </summary>
+  <int value="0" label="Request is to filesystem: URL with extension origin"/>
+  <int value="1" label="Request is to blob: URL with extension origin"/>
+  <int value="2"
+      label="Resource is not web-accessible and site URL has scheme that used
+             to be allowed"/>
+  <int value="3" label="Resource is not web-accessible (most common)"/>
+</enum>
+
 <enum name="ShutdownReason" type="int">
   <summary>
     The reason that the Chrome OS power manager shut down or rebooted the