[DOMStorage] Rate limiting writes to disk.

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 004792d95d5a77797e02d24b8f563e86c4ca6e01..a9cf12e9ced5938bb314199c63c881a7628c3026 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -5551,6 +5551,9 @@ Therefore, the affected-histogram name has to have at least one dot in it.
 </histogram>
 
 <histogram name="DOMStorage.clear" units="milliseconds">
+  <obsolete>
+    Deprecated 2012.
+  </obsolete>
   <owner>michaeln@chromium.org</owner>
   <summary>
     Duration to execute localStorage.clear() or sessionStorage.clear().
@@ -5558,6 +5561,9 @@ Therefore, the affected-histogram name has to have at least one dot in it.
 </histogram>
 
 <histogram name="DOMStorage.getItem" units="milliseconds">
+  <obsolete>
+    Deprecated 2012.
+  </obsolete>
   <owner>michaeln@chromium.org</owner>
   <summary>
     Duration to execute localStorage.getItem() or sessionStorage.getItem().
@@ -5565,6 +5571,9 @@ Therefore, the affected-histogram name has to have at least one dot in it.
 </histogram>
 
 <histogram name="DOMStorage.key" units="milliseconds">
+  <obsolete>
+    Deprecated 2012.
+  </obsolete>
   <owner>michaeln@chromium.org</owner>
   <summary>
     Duration to execute localStorage.key() or sessionStorage.key().
@@ -5572,6 +5581,9 @@ Therefore, the affected-histogram name has to have at least one dot in it.
 </histogram>
 
 <histogram name="DOMStorage.length" units="milliseconds">
+  <obsolete>
+    Deprecated 2012.
+  </obsolete>
   <owner>michaeln@chromium.org</owner>
   <summary>
     Duration to execute localStorage.length() or sessionStorage.length().
@@ -5579,6 +5591,9 @@ Therefore, the affected-histogram name has to have at least one dot in it.
 </histogram>
 
 <histogram name="DOMStorage.removeItem" units="milliseconds">
+  <obsolete>
+    Deprecated 2012.
+  </obsolete>
   <owner>michaeln@chromium.org</owner>
   <summary>
     Duration to execute localStorage.removeItem() or
@@ -5587,6 +5602,9 @@ Therefore, the affected-histogram name has to have at least one dot in it.
 </histogram>
 
 <histogram name="DOMStorage.setItem" units="milliseconds">
+  <obsolete>
+    Deprecated 2012.
+  </obsolete>
   <owner>michaeln@chromium.org</owner>
   <summary>
     Duration to execute localStorage.setItem() or sessionStorage.setItem().
@@ -12228,6 +12246,22 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="LocalStorage.Commit" enum="Boolean">
+  <owner>michaeln@chromium.org</owner>
+  <summary>
+    True is logged each time a commit occurs. False is logged each time a commit
+    is attempted during startup and deferred until later.
+  </summary>
+</histogram>
+
+<histogram name="LocalStorage.CommitDelay">
+  <owner>michaeln@chromium.org</owner>
+  <summary>
+    Delay between a page making changes and those changes being written to the
+    DB.
+  </summary>
+</histogram>
+
 <histogram name="LocalStorage.RendererLocalStorageSizeInKB" units="KB">
   <owner>michaeln@chromium.org</owner>
   <summary>