Rationalize and fix chromium android linker histogram recording.

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 38a9a3d1b5d468812a751f70f8c8e44701c98407..037da83a934b3ea02edb5d8412c33cf0c621dee6 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -2653,6 +2653,35 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="ChromiumAndroidLinker.IsUsingBrowserSharedRelros"
+    enum="BooleanEnabled">
+  <owner>simonb@chromium.org</owner>
+  <summary>
+    Whether aggressive relro sharing is enabled for the browser process.
+    Recorded once per browser run.
+  </summary>
+</histogram>
+
+<histogram name="ChromiumAndroidLinker.LoadedBrowserAtFixedAddressFailed"
+    enum="BooleanForceDisabled">
+  <owner>simonb@chromium.org</owner>
+  <summary>
+    Whether relro sharing was attempted for the browser but did not succeed,
+    forcing back-off to non-shared relros. NOTE: If the browser cannnot load at
+    a fixed address, relro sharing is also disabled for all renderers. Recorded
+    once per browser run.
+  </summary>
+</histogram>
+
+<histogram name="ChromiumAndroidLinker.LoadedRendererAtFixedAddressFailed"
+    enum="BooleanForceDisabled">
+  <owner>simonb@chromium.org</owner>
+  <summary>
+    Whether relro sharing was attempted for a renderer but did not succeed,
+    forcing back-off to non-shared relros. Recorded for each renderer.
+  </summary>
+</histogram>
+
 <histogram name="clickjacking.discard_download" units="ms">
   <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
   <summary>