Push API: Return cached registration if available.

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 84859fed502f94effaf0f3cf20a853d5d8b72226..836481a524f00490622c61896e5e33b504936fb2 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -53740,13 +53740,14 @@ To add a new entry, add it with any value and run test to compute valid value.
 
 <enum name="PushRegistrationStatus" type="int">
   <int value="0" label="Successful"/>
-  <int value="1" label="Page has no active Service Worker"/>
-  <int value="2" label="Push service not available"/>
-  <int value="3" label="Registration limit reached"/>
-  <int value="4" label="Permission denied"/>
-  <int value="5" label="Push service error"/>
-  <int value="6" label="No sender id provided"/>
-  <int value="7" label="Storage error"/>
+  <int value="1" label="Successful (from cache)"/>

[Ilya Sherman, 2014/12/09 00:30:53]

Is the is a subcase of case 0, or complementary?  Please clarify in the labels.

[johnme, 2014/12/11 16:15:17]

Done.

+  <int value="2" label="Page has no active Service Worker"/>
+  <int value="3" label="Push service not available"/>
+  <int value="4" label="Registration limit reached"/>
+  <int value="5" label="Permission denied"/>
+  <int value="6" label="Push service error"/>
+  <int value="7" label="No sender id provided"/>
+  <int value="8" label="Storage error"/>
 </enum>
 
 <enum name="QuicAddressMismatch" type="int">