Enable various V8 garbage collection timing foreground and background metrics on UMA.

The V8-side landed in: https://chromium-review.googlesource.com/c/v8/v8/+/981146

Bug: chromium:814144
Change-Id: I3ef9523b4a0f371ce0f22400ef3c70bb521117ee
Reviewed-on: https://chromium-review.googlesource.com/999472
Commit-Queue: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550225}

tools/metrics/histograms/histograms.xml

@@ -98646,6 +98646,20 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>Time spent in mark-sweep phase of GC.</summary>
 </histogram>
 
+<histogram name="V8.GCCompactorBackground" units="ms">
+  <owner>hpayer@chromium.org</owner>
+  <summary>
+    Time spent in mark-sweep phase of GC in a background isolate.
+  </summary>
+</histogram>
+
+<histogram name="V8.GCCompactorForeground" units="ms">
+  <owner>hpayer@chromium.org</owner>
+  <summary>
+    Time spent in mark-sweep phase of GC in a foreground isolate.
+  </summary>
+</histogram>
+
 <histogram name="V8.GCContext" units="ms">
   <owner>hpayer@chromium.org</owner>
   <summary>Time spent doing a full GC during an IdleNotification.</summary>
@@ -98657,6 +98671,24 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>Time spent in finalize incremental mark-sweep phase of GC.</summary>
 </histogram>
 
+<histogram name="V8.GCFinalizeMCBackground" units="ms">
+  <owner>ulan@chromium.org</owner>
+  <owner>hpayer@chromium.org</owner>
+  <summary>
+    Time spent in finalize incremental mark-sweep phase of GC in a background
+    isolate.
+  </summary>
+</histogram>
+
+<histogram name="V8.GCFinalizeMCForeground" units="ms">
+  <owner>ulan@chromium.org</owner>
+  <owner>hpayer@chromium.org</owner>
+  <summary>
+    Time spent in finalize incremental mark-sweep phase of GC in a foreground
+    isolate.
+  </summary>
+</histogram>
+
 <histogram name="V8.GCFinalizeMCReduceMemory" units="ms">
   <owner>ulan@chromium.org</owner>
   <owner>hpayer@chromium.org</owner>
@@ -98665,14 +98697,22 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
-<histogram name="V8.GCFinalzeMC" units="ms">
-  <obsolete>
-    This histogram has been replaced by V8.GCFinalizeMC because of typo in the
-    name.
-  </obsolete>
+<histogram name="V8.GCFinalizeMCReduceMemoryBackground" units="ms">
   <owner>ulan@chromium.org</owner>
   <owner>hpayer@chromium.org</owner>
-  <summary>Time spent in finalize incremental mark-sweep phase of GC.</summary>
+  <summary>
+    Time spent in finalize incremental memory-reducing mark-sweep phase of GC in
+    a background isolate.
+  </summary>
+</histogram>
+
+<histogram name="V8.GCFinalizeMCReduceMemoryForeground" units="ms">
+  <owner>ulan@chromium.org</owner>
+  <owner>hpayer@chromium.org</owner>
+  <summary>
+    Time spent in finalize incremental memory-reducing mark-sweep phase of GC in
+    a foreground isolate.
+  </summary>
 </histogram>
 
 <histogram name="V8.GCIdleNotification" units="ms">
@@ -98751,11 +98791,25 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>Time spent in scavenging phase of GC.</summary>
 </histogram>
 
+<histogram name="V8.GCScavengerBackground" units="ms">
+  <owner>hpayer@chromium.org</owner>
+  <summary>
+    Time spent in scavenging phase of GC in a background isolate.
+  </summary>
+</histogram>
+
 <histogram name="V8.GCScavengeReason" enum="GarbageCollectionReason">
   <owner>ulan@chromium.org</owner>
   <summary>Reason a scavenge garbage collection was started in V8.</summary>
 </histogram>
 
+<histogram name="V8.GCScavengerForeground" units="ms">
+  <owner>hpayer@chromium.org</owner>
+  <summary>
+    Time spent in scavenging phase of GC in a foreground isolate.
+  </summary>
+</histogram>
+
 <histogram name="V8.GCYoungGenerationHandling" enum="YoungGenerationHandling">
   <owner>mlippautz@chromium.org</owner>
   <summary>