UMA for previews infobar and Lo-Fi context menu items

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 9bcf215df1130c91b8c57c6db1819f79215ea970..994d1b9661d459c6a4ef789d950f0d99514f2345 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -8037,6 +8037,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="DataReductionProxy.LoFi.UIAction"
     enum="DataReductionProxyLoFiUIAction">
+  <obsolete>
+    Deprecated as of 9/2016, replaced by Previews.ContextMenuAction.LoFi.
+  </obsolete>
   <owner>bengr@chromium.org</owner>
   <owner>megjablon@chromium.org</owner>
   <summary>
@@ -45994,6 +45997,59 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Previews.ContextMenuAction.LoFi"

[Alexei Svitkine (slow), 2016/09/08 17:13:41]

This seems to be adding a new top level prefix - "Previews.". In general, we try
to suggest to re-use an existing prefix unless we expect the new category to be
extensively used. I'm not sure which case this is, however I find the name not
super obvious to me - "Previews" doesn't tell me very much. Regardless if it
will be top level or nested under something, I encourage using a name that's a
bit clearer what it's about - to developers who do not work directly on the
feature. Do you have suggestions for such a name?

And for my own benefit, what is the "previews" feature?

[megjablon, 2016/09/08 18:26:13]

Previews is the name for all features that rewrite the page to improve data
efficiency and load latency. It includes features that use the data reduction
proxy, but also client-side rewrites that aren't appropriate to nest under the
proxy's name. Here's the design doc that summarizes all these efforts:
https://docs.google.com/a/google.com/document/d/1MYTA8pjWFNvICQpcXzAr22ggJjgQ....

[Alexei Svitkine (slow), 2016/09/08 20:32:07]

I see, so it's a project codename? I'm still not a fan of the prefix since I
would imagine very few people outside your team would understand it. Would a
more explanatory name prefix like "PageRewriter." be acceptable?

[megjablon, 2016/09/08 23:24:47]

We've already started using this name throughout the code. We have a component
named this as well. I'll defer to bengr@ on the decision of if we want to do a
rename.

+    enum="PreviewsContextMenuActionLoFi">
+  <owner>bengr@chromium.org</owner>
+  <owner>megjablon@chromium.org</owner>
+  <summary>
+    Samples of user interactions with the Lo-Fi context menu options. These
+    samples include:
+
+    Displays and clicks on the &quot;Load image&quot; and &quot;Load
+    images&quot; context menu options. Count of pages where the user has clicked
+    &quot;Load image&quot; at least once.
+  </summary>
+</histogram>
+
+<histogram name="Previews.InfoBarAction.LitePage" enum="PreviewsInfoBarAction">
+  <owner>bengr@chromium.org</owner>
+  <owner>megjablon@chromium.org</owner>
+  <summary>
+    Samples of user interactions with the previews LitePage &quot;Saved
+    data&quot; infobar. These samples include:
+
+    Displays of the infobar and clicks on the &quot;Load original&quot; link.
+    Whether the infobar was dismissed by navigation or the user clicking on
+    &quot;X&quot; close button.
+  </summary>
+</histogram>
+
+<histogram name="Previews.InfoBarAction.LoFi" enum="PreviewsInfoBarAction">
+  <owner>bengr@chromium.org</owner>
+  <owner>megjablon@chromium.org</owner>
+  <summary>
+    Samples of user interactions with the previews Lo-Fi &quot;Saved data&quot;
+    infobar. These samples include:
+
+    Displays of the infobar and clicks on the &quot;Load original&quot; link.
+    Whether the infobar was dismissed by navigation or the user clicking on
+    &quot;X&quot; close button.
+  </summary>
+</histogram>
+
+<histogram name="Previews.InfoBarAction.Offline" enum="PreviewsInfoBarAction">
+  <owner>bengr@chromium.org</owner>
+  <owner>megjablon@chromium.org</owner>
+  <summary>
+    Samples of user interactions with the previews Offline &quot;Faster page
+    loaded&quot; infobar. These samples include:
+
+    Displays of the infobar and clicks on the &quot;Load original&quot; link.
+    Whether the infobar was dismissed by navigation or the user clicking on
+    &quot;X&quot; close button.
+  </summary>
+</histogram>
+
 <histogram name="PrinterService.PrinterServiceEvent"
     enum="PrinterServiceEventType">
   <owner>vitalybuka@chromium.org</owner>
@@ -90965,6 +91021,22 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="3" label="tapdown + tapunconfirmed"/>
 </enum>
 
+<enum name="PreviewsContextMenuActionLoFi" type="int">
+  <int value="0" label="'Load image' context menu item shown"/>
+  <int value="1" label="'Load image' context menu item clicked"/>
+  <int value="2"
+      label="Pages where the user has clicked 'Load image' at least once"/>
+  <int value="3" label="'Load images' context menu item shown"/>
+  <int value="4" label="'Load images' context menu item clicked"/>
+</enum>
+
+<enum name="PreviewsInfoBarAction" type="int">
+  <int value="0" label="Infobar shown"/>
+  <int value="1" label="Infobar 'Load original' clicked"/>
+  <int value="2" label="Infobar dismissed by user"/>
+  <int value="3" label="Infobar dismissed by navigation"/>
+</enum>
+
 <enum name="PrinterServiceEventType" type="int">
   <int value="0" label="Printer added"/>
   <int value="1" label="Page displayed (Deprecated)"/>