Rejig stability intstrumentation filenames and targets

The main change is to rename postmortem_report_extractor to stability_report_extractor, and pull it out to a separate target. We want to use this not only postmortem, but also on crash.

BUG=620813

Review-Url: https://codereview.chromium.org/2856923002
Cr-Commit-Position: refs/heads/master@{#469438}
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index fc0752c..28a0089 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -3710,7 +3710,7 @@
       "//chrome_elf:dll_hash",
       "//components/browser_watcher",
       "//components/browser_watcher:browser_watcher_client",
-      "//components/browser_watcher:stability_data",
+      "//components/browser_watcher:stability_client",
       "//google_update",
       "//third_party/crashpad/crashpad/client:client",
       "//third_party/iaccessible2",