Refactor CrashDump*Manager to use a shared CrashDumpObserver singleton.

components/crash/content/browser/crash_dump_observer_android.h

+// Copyright 2015 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.
+
+#ifndef COMPONENTS_CRASH_CONTENT_BROWSER_CRASH_DUMP_OBSERVER_ANDROID_H_
+#define COMPONENTS_CRASH_CONTENT_BROWSER_CRASH_DUMP_OBSERVER_ANDROID_H_
+
+#include <memory>
+#include <vector>
+
+#include "base/android/application_status_listener.h"
+#include "base/lazy_instance.h"
+#include "base/memory/ref_counted.h"
+#include "base/process/kill.h"
+#include "base/process/process.h"
+#include "content/public/browser/browser_child_process_observer.h"
+#include "content/public/browser/file_descriptor_info.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
+#include "content/public/common/process_type.h"
+
+namespace breakpad {
+
+// This class centralises the observation of child processes for the
+// purpose of reacting to child process crashes.
+// The CrashDumpObserver instance exists on the browser main thread.
+class CrashDumpObserver : public content::BrowserChildProcessObserver,
+                          public content::NotificationObserver {
+ public:
+  // CrashDumpObserver client interface.
+  // Client methods will be called synchronously in the order in which
+  // clients were registered. It is the implementer's responsibility
+  // to post tasks to the appropriate threads if required (and be
+  // aware that this may break ordering guarantees).
+  class Client {
+   public:
+    // OnChildStart is called on the launcher thread.
+    virtual void OnChildStart(int child_process_id,
+                              content::FileDescriptorInfo* mappings) = 0;
+    // OnChildExit is called on the UI thread.
+    // OnChildExit may be called twice (once for the child process
+    // termination, and once for the IPC channel disconnection).
+    virtual void OnChildExit(int child_process_id,
+                             base::ProcessHandle pid,
+                             content::ProcessType process_type,
+                             base::TerminationStatus termination_status,
+                             base::android::ApplicationState app_state) = 0;
+
+    virtual ~Client() {}
+  };
+
+  // The global CrashDumpObserver instance is created by calling
+  // Create (on the UI thread), and lives until process exit. Tests
+  // making use of this class should register an AtExitManager.
+  static void Create();
+  // Fetch a pointer to the global CrashDumpObserver instance. The

[Bernhard Bauer, 2016/12/08 17:41:25]

Nit: empty line before the comment?

[Tobias Sargeant, 2016/12/12 11:49:51]

Done.

+  // global instance must have been created by the time GetInstance is
+  // called.
+  static CrashDumpObserver* GetInstance();
+
+  void RegisterClient(std::unique_ptr<Client> client);
+
+  // BrowserChildProcessStarted must be called from
+  // ContentBrowserClient::GetAdditionalMappedFilesForChildProcess
+  // overrides, to notify the CrashDumpObserver of child process
+  // creation, and to allow clients to register any fd mappings they
+  // need.
+  void BrowserChildProcessStarted(int child_process_id,
+                                  content::FileDescriptorInfo* mappings);
+
+ private:
+  friend struct base::DefaultLazyInstanceTraits<CrashDumpObserver>;
+
+  CrashDumpObserver();
+  ~CrashDumpObserver() override;
+
+  // content::BrowserChildProcessObserver implementation:
+  void BrowserChildProcessHostDisconnected(
+      const content::ChildProcessData& data) override;
+  void BrowserChildProcessCrashed(const content::ChildProcessData& data,
+                                  int exit_code) override;
+  // On Android we will never observe BrowserChildProcessCrashed
+  // because we do not receive exit codes from zygote spawned
+  // processes.
+
+  // NotificationObserver implementation:
+  void Observe(int type,
+               const content::NotificationSource& source,
+               const content::NotificationDetails& details) override;
+
+  // Called on child process exit (including crash).
+  void OnChildExit(int child_process_id,
+                   base::ProcessHandle pid,
+                   content::ProcessType process_type,
+                   base::TerminationStatus termination_status,
+                   base::android::ApplicationState app_state);
+
+  content::NotificationRegistrar notification_registrar_;
+
+  base::Lock registered_clients_lock_;
+  std::vector<std::unique_ptr<Client>> registered_clients_;
+
+  DISALLOW_COPY_AND_ASSIGN(CrashDumpObserver);
+};
+
+}  // namespace breakpad
+
+#endif  // COMPONENTS_CRASH_CONTENT_BROWSER_CRASH_DUMP_OBSERVER_ANDROID_H_