Emit UMAs for metrics from memory instrumentation service.

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 ba76f7beb6b4bdfe4607da6ff100bfc540735407..bc130705ee0876e527b33fe869efe05ae665a3c3 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -29529,6 +29529,16 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram base="true" name="Memory.Experimental.Browser2" units="MB">
+<!-- Name completed by histogram_suffixes name="BrowserMemoryAllocator2" -->
+
+  <owner>erikchen@chromium.org</owner>
+  <summary>
+    The browser process's memory usage reported by the memory instrumentation
+    service.
+  </summary>
+</histogram>
+
 <histogram name="Memory.Experimental.CompressedPagesPerSecond" units="pages/s">
   <owner>bashi@chromium.org</owner>
   <summary>
@@ -29556,6 +29566,16 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram base="true" name="Memory.Experimental.Gpu2" units="MB">
+<!-- Name completed by histogram_suffixes name="GpuMemoryAllocator2" -->
+
+  <owner>erikchen@chromium.org</owner>
+  <summary>
+    The gpu process's memory usage reported by the memory instrumentation
+    service.
+  </summary>
+</histogram>
+
 <histogram base="true" name="Memory.Experimental.Renderer" units="MB">
 <!-- Name completed by histogram_suffixes name="RendererMemoryAllocator" -->
 
@@ -29589,6 +29609,16 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram base="true" name="Memory.Experimental.Renderer2" units="MB">
+<!-- Name completed by histogram_suffixes name="RendererMemoryAllocator2" -->
+
+  <owner>erikchen@chromium.org</owner>
+  <summary>
+    The renderer process's memory usage reported by the memory instrumentation
+    service.
+  </summary>
+</histogram>
+
 <histogram name="Memory.Experimental.SwapInPerSecond" units="swaps/s">
   <owner>bashi@chromium.org</owner>
   <summary>
@@ -83783,6 +83813,12 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <affected-histogram name="BlinkGC.CollectionRate"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="BrowserMemoryAllocator2" separator=".">
+  <suffix name="Resident" label="Only counting resident memory."/>
+  <suffix name="Malloc" label="Constrained to malloc allocator."/>
+  <affected-histogram name="Memory.Experimental.Browser2"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="CachedResourceType" separator=".">
   <suffix name="JavaScript"
       label="Showing cache patterns only for JavaScript resources."/>
@@ -85751,6 +85787,12 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <affected-histogram name="GPU.ContextMemory.WebGL"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="GpuMemoryAllocator2" separator=".">
+  <suffix name="Resident" label="Only counting resident memory."/>
+  <suffix name="Malloc" label="Constrained to malloc allocator."/>
+  <affected-histogram name="Memory.Experimental.Gpu2"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="GWSChromeJointExperiment">
   <suffix name="Experiment1"
       label="Only page loads that are a result of a navigation from a web
@@ -90453,6 +90495,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <affected-histogram name="Memory.Experimental.Renderer"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="RendererMemoryAllocator2" separator=".">
+  <suffix name="Resident" label="Only counting resident memory."/>
+  <suffix name="Malloc" label="Constrained to malloc allocator."/>
+  <suffix name="PartitionAlloc" label="Constrained to partition allocator."/>
+  <suffix name="BlinkGC" label="Constrained to blink GC allocator."/>
+  <suffix name="V8" label="Constrained to v8 allocator."/>
+  <affected-histogram name="Memory.Experimental.Renderer2"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="RendererMemoryTiming" separator=".">
   <suffix name="DidFinishLoad"
       label="Recorded each time DidFinishLoad is called for *any* frame