Validate hash_sha256 checksum on .crx update.

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 c01faf0ae982b5f3caea97196f58386425be659a..a369563816b9d4134eccdb1a60ac6f62f419366f 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -8946,6 +8946,13 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <summary>Time taken to unpack an extension, when the unpack fails.</summary>
 </histogram>
 
+<histogram name="Extensions.SandboxUnpackHashCheck">

[Ilya Sherman, 2015/02/03 21:41:17]

Actually, please also associate an enum with this histogram.  I'm thinking the
values would be something like "Valid hash sum" and "Invalid hash sum".

+  <owner>ginkage@chromium.org</owner>
+  <summary>
+    Whether a CRX file hash sum was the same as in an updater manifest.
+  </summary>
+</histogram>
+
 <histogram name="Extensions.SandboxUnpackInitialCrxPathLength">
   <owner>asargent@chromium.org</owner>
   <summary>Length of the initial path to the CRX to be unpacked.</summary>
@@ -47418,6 +47425,7 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="30" label="INVALID_PATH_FOR_CATALOG"/>
   <int value="31" label="ERROR_SERIALIZING_CATALOG"/>
   <int value="32" label="ERROR_SAVING_CATALOG"/>
+  <int value="33" label="CRX_HASH_VERIFICATION_FAILED"/>
 </enum>
 
 <enum name="ExternalDeviceAction" type="int">