Photo Picker dialog: Add UMA statistics.

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 81ea29002ff6ed11368beaf02cfa13a30a2eb440..f621f168e363dbd25fa82f6e379ebfa6ba92e69d 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -871,6 +871,72 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Android.PhotoPicker.BitmapScalerTask" units="ms">
+  <owner>finnur@chromium.org</owner>
+  <owner>twellington@chromium.org</owner>
+  <summary>
+    Measures the amount of time the BitmapScaler spends scaling per bitmap.
+  </summary>
+</histogram>
+
+<histogram name="Android.PhotoPicker.CacheHits" units="Hits">
+  <owner>finnur@chromium.org</owner>
+  <owner>twellington@chromium.org</owner>
+  <summary>
+    Measures how often an image is served from the high-res cache while the
+    dialog is open.
+  </summary>
+</histogram>
+
+<histogram name="Android.PhotoPicker.DecodeRequests" units="Hits">
+  <owner>finnur@chromium.org</owner>
+  <owner>twellington@chromium.org</owner>
+  <summary>
+    Measures how often an image is sent for decoding while the dialog is open.
+  </summary>
+</histogram>
+
+<histogram name="Android.PhotoPicker.DialogAction"
+    enum="PhotoPickerDialogAction">
+  <owner>finnur@chromium.org</owner>
+  <owner>twellington@chromium.org</owner>
+  <summary>
+    Records which action the user takes in the PhotoPickerDialog.
+  </summary>
+</histogram>
+
+<histogram name="Android.PhotoPicker.ImageByteCount" units="KB">
+  <owner>finnur@chromium.org</owner>
+  <owner>twellington@chromium.org</owner>
+  <summary>Measures the bytecount of a decoded image.</summary>

[Theresa, 2017/06/02 15:40:22]

nit: s/bytecount/byte count

+</histogram>
+
+<histogram name="Android.PhotoPicker.ImageDecodeTime" units="ms">
+  <owner>finnur@chromium.org</owner>
+  <owner>twellington@chromium.org</owner>
+  <summary>
+    Measures the amount of time it takes the decoder to decode one image.
+  </summary>
+</histogram>
+
+<histogram name="Android.PhotoPicker.RequestProcessTime" units="ms">
+  <owner>finnur@chromium.org</owner>
+  <owner>twellington@chromium.org</owner>
+  <summary>
+    Measures the amount of time it takes to process one decode request end to
+    end (RPC and actual decoding of the bits by utility process).
+  </summary>
+</histogram>
+
+<histogram name="Android.PhotoPicker.UpscaleLowResBitmap" units="ms">
+  <owner>finnur@chromium.org</owner>
+  <owner>twellington@chromium.org</owner>
+  <summary>
+    Measures the amount of time it takes to upscale a bitmap from the low-res
+    cache.
+  </summary>
+</histogram>
+
 <histogram name="Android.PrepareMenu.OpenWebApkVisibilityCheck" units="ms">
   <owner>hanxi@chromium.org</owner>
   <owner>pkotwicz@chromium.org</owner>