BackForwardCache: Add metrics for the reason why the page is evicted

This adds new metrics for eviction by back-forward navigation:
BackForwardCache.EvictedReason.

BackForwardCache.EvictedReason records the reason why the page is
evicted, e.g., by JavaScript execution.

This CL is a split of the CL for all the metrices:
https://chromium-review.googlesource.com/c/chromium/src/+/1782233

Bug: 1004676
Change-Id: Ieea66f2ae6ed30fb836262632ab39b450698a6e9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1820701
Commit-Queue: Hajime Hoshi <[email protected]>
Reviewed-by: Arthur Sonzogni <[email protected]>
Reviewed-by: Kinuko Yasuda <[email protected]>
Reviewed-by: Alexander Timin <[email protected]>
Reviewed-by: Kouhei Ueno <[email protected]>
Cr-Commit-Position: refs/heads/master@{#704546}
diff --git a/content/browser/site_instance_impl.cc b/content/browser/site_instance_impl.cc
index 2cee6bf..b5efd8f5 100644
--- a/content/browser/site_instance_impl.cc
+++ b/content/browser/site_instance_impl.cc
@@ -986,7 +986,7 @@
     RenderProcessHost* host,
     const ChildProcessTerminationInfo& info) {
   for (auto& observer : observers_)
-    observer.RenderProcessGone(this);
+    observer.RenderProcessGone(this, info);
 }
 
 void SiteInstanceImpl::LockToOriginIfNeeded() {