Refactor CrashDump*Manager to use a shared CrashDumpObserver singleton.

components/crash/content/browser/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 if (is_android) {
   import("//build/config/android/config.gni")
 }
 
 source_set("browser") {
   sources = [
     "crash_dump_manager_android.cc",
     "crash_dump_manager_android.h",
-    "crash_micro_dump_manager_android.cc",
-    "crash_micro_dump_manager_android.h",
+    "crash_dump_observer_android.cc",
+    "crash_dump_observer_android.h",
   ]
 
   deps = [
     "//base",
     "//breakpad:client",
     "//components/crash/content/app",
     "//content/public/browser",
     "//content/public/common",
   ]
 
@@ skipping 11 matching lines @@
     ]
   }
 
   # This is not in the GYP build but this target includes breakpad client
   # headers, so add the dependency here.
   if (is_posix && !is_ios) {
     configs += [ "//breakpad:client_config" ]
     public_configs = [ "//breakpad:client_config" ]
   }
 }