Use Android callback API to obtain cellular signal strength

tools/metrics/histograms/enums.xml

Index: tools/metrics/histograms/enums.xml
diff --git a/tools/metrics/histograms/enums.xml b/tools/metrics/histograms/enums.xml
index 196c83bbc1f9a9c732a9df8360a239ea67290648..a13a9a58b3dff0d7a837967d0525bbbecf032bb6 100644
--- a/tools/metrics/histograms/enums.xml
+++ b/tools/metrics/histograms/enums.xml
@@ -2588,13 +2588,13 @@ uploading your change for review.  These are checked by presubmit scripts.
   <int value="4" label="Bad disable reasons"/>
 </enum>
 
-<enum name="BankNameDisplayedFormEvent" type="int">
+<enum name="BankNameDisplayedFormEvent">
   <int value="0" label="Suggestions shown with bank name available (once)"/>
   <int value="1"
       label="Server suggestion filled with bank name available (once)"/>
 </enum>
 
-<enum name="BaseRelocationType" type="int">
+<enum name="BaseRelocationType">
   <int value="0" label="IMAGE_REL_BASED_ABSOLUTE"/>
   <int value="1" label="IMAGE_REL_BASED_HIGH"/>
   <int value="2" label="IMAGE_REL_BASED_LOW"/>
@@ -35962,7 +35962,7 @@ from previous Chrome versions.
   <int value="3" label="Infobar dismissed"/>
 </enum>
 
-<enum name="ThumbnailTopSitesEvent" type="int">
+<enum name="ThumbnailTopSitesEvent">
   <int value="0" label="Not added: Failure"/>
   <int value="1" label="Not added: TopSites is full"/>
   <int value="2" label="Not added: Existing thumbnail is better"/>