Implement the renderer side of the mojo based local storage implementation.

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 ba8aa2e7d974703b9e82056b9b0ae5905c399184..bb39b4be82068a1938653709bae5732a0aae0e9b 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -18790,6 +18790,30 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="LocalStorage.MojoSizeInKB" units="KB">
+  <owner>jam@chromium.org</owner>
+  <summary>
+    Size of the HTML5 LocalStorage DB in KB in the renderer-side cache using
+    Mojo implementation.
+  </summary>
+</histogram>
+
+<histogram name="LocalStorage.MojoTimeToPrime">

[Ilya Sherman, 2016/03/18 21:46:14]

Please specify the units.

[jam, 2016/03/18 22:15:01]

Done.

+  <owner>jam@chromium.org</owner>
+  <summary>
+    Time to load HTML5 LocalStorage into the renderer-side cache using Mojo
+    implementation.
+  </summary>
+</histogram>
+
+<histogram name="LocalStorage.MojoTimeToPrimeFor">

[Ilya Sherman, 2016/03/18 21:46:14]

Please specify the units.

[jam, 2016/03/18 22:15:01]

Done.

+  <owner>jam@chromium.org</owner>
+  <summary>
+    Time to load HTML5 LocalStorage into the renderer-side cache using Mojo
+    implementation, split by size.
+  </summary>
+</histogram>
+
 <histogram name="LocalStorage.RendererLocalStorageSizeInKB" units="KB">
   <owner>michaeln@chromium.org</owner>
   <summary>
@@ -86409,6 +86433,7 @@ To add a new entry, add it with any value and run test to compute valid value.
   <suffix name="100KBTo1MB" label="DB size between 100KB and 1MB"/>
   <suffix name="1MBTo5MB" label="DB size between 1MB and 5MB"/>
   <affected-histogram name="LocalStorage.BrowserTimeToPrimeLocalStorage"/>
+  <affected-histogram name="LocalStorage.MojoTimeToPrimeFor"/>
   <affected-histogram name="LocalStorage.RendererTimeToPrimeLocalStorage"/>
 </histogram_suffixes>