Revert CompressibleString (and its UMA)

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 00fc159afce5b19a8027bb3adc0a39fec5000c4f..a2b3efc4e208263d936a4d929d64ae72a2e15272 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -23612,19 +23612,6 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
-<histogram name="Memory.CompressibleStringCount"
-    enum="CompressibleStringCountType">

[Ilya Sherman, 2016/08/09 19:15:19]

Please mark this histogram as <obsolete> rather than removing it.

[hajimehoshi, 2016/08/10 06:17:34]

Done.

-  <owner>hajimehoshi@chromium.org</owner>
-  <summary>
-    This records the frequency with which JavaScript source strings are
-    compressed and decompressed in foreground and background tabs.  Compressing
-    runs 10 seconds after the tab goes background and decompressing runs when
-    JavaScript source string is required (e.g. V8 starts to compile). This
-    measurement is a preparation to introduce CompressibleString class for
-    JavaScript source strings to reduce Blink memory usage.
-  </summary>
-</histogram>
-
 <histogram name="Memory.DiscardableAllocationSize" units="KB">
   <owner>reveman@chromium.org</owner>
   <summary>
@@ -70532,11 +70519,6 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="1" label="GPU compositor"/>
 </enum>
 
-<enum name="CompressibleStringCountType" type="int">
-  <int value="0" label="Compressed in a background tab"/>
-  <int value="1" label="Decompressed in a background or a foreground tab"/>
-</enum>
-
 <enum name="ComputeCurrentSigninStatus" type="int">
   <obsolete>
     Deprecated as of Jun 2016. The enum was added for debugging purpose and is