Add Drive.MetadataDBValidityCheckFailureReason UMA histogram

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 9ef66e50e646f39727ae34f685e46621f02157e3..3fb40bd3d8a3a4f859a13d2f2655cd4ca304213d 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -5289,6 +5289,16 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="Drive.MetadataDBValidityCheckFailureReason"
+    enum="DriveMetadataDBValidityCheckFailureReason">
+  <owner>joshwoodward@google.com</owner>

[Alexei Svitkine (slow), 2014/08/06 15:55:48]

Nit: @chromium.org accounts are generally preferred. Also, shouldn't you be the
owner of this metric? We do support multiple owner tags if there's more than one
person who should be listed.

[hashimoto, 2014/08/07 04:32:01]

Replaced with chromium.org accounts of appropriate owners.

+  <summary>
+    Reason of drive resource metadata database validity check failure. Recorded
+    when the validity check fails during Drive metadata initialization triggered
+    by profile initialization.
+  </summary>
+</histogram>
+
 <histogram name="Drive.MetadataDBVersionBeforeUpgradeCheck">
   <owner>joshwoodward@google.com</owner>
   <summary>
@@ -37919,6 +37929,17 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="9" label="Cannot open existing DB. Created new DB."/>
 </enum>
 
+<enum name="DriveMetadataDBValidityCheckFailureReason" type="int">
+  <int value="0" label="Invalid header"/>
+  <int value="1" label="Broken ID entry"/>
+  <int value="2" label="Broken entry"/>
+  <int value="3" label="Invalid local ID"/>
+  <int value="4" label="Invalid parent ID"/>
+  <int value="5" label="Broken child map"/>
+  <int value="6" label="Child entry count mismatch"/>
+  <int value="7" label="Iterator error"/>
+</enum>
+
 <enum name="EAPInnerProtocol" type="int">
   <int value="0" label="UNKNOWN"/>
   <int value="1" label="NONE"/>