[Downloads UI] Add histograms for file extensions

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 6da57af7e8f435da142bf434517a410bd19cba20..18531fde552d0c2990390739b7c3f674d3e9c12d 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -465,6 +465,46 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>Recorded when a download is opened.</summary>
 </histogram>
 
+<histogram name="Android.DownloadManager.OtherExtensions.InitialCount"
+    enum="AndroidDownloadExtensionType">
+  <owner>dfalcantara@chromium.org</owner>
+  <owner>twellington@chromium.org</owner>
+  <summary>
+    The extension type for non-incognito download items that match the
+    &quot;other&quot; filter type. Recorded when the download UI is initialized.
+  </summary>
+</histogram>
+
+<histogram name="Android.DownloadManager.OtherExtensions.OpenFailed"
+    enum="AndroidDownloadExtensionType">
+  <owner>dfalcantara@chromium.org</owner>
+  <owner>twellington@chromium.org</owner>
+  <summary>
+    The extension type for downloads that match the &quot;other&quot; filter
+    type. Recorded when a download fails to open.
+  </summary>
+</histogram>
+
+<histogram name="Android.DownloadManager.OtherExtensions.OpenSucceeded"
+    enum="AndroidDownloadExtensionType">
+  <owner>dfalcantara@chromium.org</owner>
+  <owner>twellington@chromium.org</owner>
+  <summary>
+    The extension type for downloads that match the &quot;other&quot; filter
+    type. Recorded when a download is opened.
+  </summary>
+</histogram>
+
+<histogram name="Android.DownloadManager.OtherExtensions.Share"
+    enum="AndroidDownloadExtensionType">
+  <owner>dfalcantara@chromium.org</owner>
+  <owner>twellington@chromium.org</owner>
+  <summary>
+    The extension type for downloads that match the &quot;other&quot; filter
+    type. Recorded when downloads are shared through the download manager.
+  </summary>
+</histogram>
+
 <histogram name="Android.DownloadManager.Share.Count">
   <owner>dfalcantara@chromium.org</owner>
   <owner>twellington@chromium.org</owner>
@@ -74283,6 +74323,24 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="1" label="NEON support"/>
 </enum>
 
+<enum name="AndroidDownloadExtensionType" type="int">
+  <int value="0" label="Other"/>
+  <int value="1" label="APK"/>
+  <int value="2" label="CSV"/>
+  <int value="3" label="DOC"/>
+  <int value="4" label="DOCX"/>
+  <int value="5" label="EXE"/>
+  <int value="6" label="PDF"/>
+  <int value="7" label="PPT"/>
+  <int value="8" label="PPTX"/>
+  <int value="9" label="PSD"/>
+  <int value="10" label="RTF"/>
+  <int value="11" label="TXT"/>
+  <int value="12" label="XLS"/>
+  <int value="13" label="XLSX"/>
+  <int value="14" label="ZIP"/>
+</enum>
+
 <enum name="AndroidDownloadFilterType" type="int">
   <int value="0" label="All"/>
   <int value="1" label="Page"/>