Refactor CrashDump*Manager to use a shared CrashDumpObserver singleton.

android_webview/browser/aw_browser_main_parts.h

Index: android_webview/browser/aw_browser_main_parts.h
diff --git a/android_webview/browser/aw_browser_main_parts.h b/android_webview/browser/aw_browser_main_parts.h
index 8d4671f6dd6f761efc697d6d24495482530296f0..a58b7cd82b6342ab6ed78b47e15e8d62201ce2c7 100644
--- a/android_webview/browser/aw_browser_main_parts.h
+++ b/android_webview/browser/aw_browser_main_parts.h
@@ -15,6 +15,10 @@ namespace base {
 class MessageLoop;
 }
 
+namespace breakpad {
+class CrashDumpObserver;
+}
+
 namespace android_webview {
 
 class AwBrowserContext;
@@ -34,6 +38,7 @@ class AwBrowserMainParts : public content::BrowserMainParts {
  private:
   // Android specific UI MessageLoop.
   std::unique_ptr<base::MessageLoop> main_message_loop_;
+  std::unique_ptr<breakpad::CrashDumpObserver> crash_dump_observer_;
 
   AwContentBrowserClient* browser_client_;