[win] Change Chrome Watcher configuration API.

chrome/app/chrome_watcher_command_line_win.h

Index: chrome/app/chrome_watcher_command_line_win.h
diff --git a/chrome/app/chrome_watcher_command_line_win.h b/chrome/app/chrome_watcher_command_line_win.h
index d4d4a97dba0b3e3ebf80b67c0302ed6e63225504..b80b85740c2eb1daa9cc0470614b421991f8769c 100644
--- a/chrome/app/chrome_watcher_command_line_win.h
+++ b/chrome/app/chrome_watcher_command_line_win.h
@@ -6,13 +6,102 @@
 #define CHROME_APP_CHROME_WATCHER_COMMAND_LINE_WIN_H_
 
 #include <windows.h>
+#include <vector>
 
+#include "base/command_line.h"
+#include "base/files/file_path.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/win/scoped_handle.h"
 
-namespace base {
-class CommandLine;
-class FilePath;
-}  // namespace base
+// Class for configuring the Chrome watcher process via the command-line. This
+// accepts configuration from the parent process and generates the required
+// command-line.
+//
+// It provides functionality for the common task of sharing handles from a
+// parent to a child process, automatically duplicating them with the
+// appropriate permissions. These handles are closed when the generator is
+// destroyed so the generator must outlive the process creation.
+class ChromeWatcherCommandLineGenerator {
+ public:
+  explicit ChromeWatcherCommandLineGenerator(const base::FilePath& chrome_exe);
+
+  // Sets a handle to be shared with the child process. This will duplicate the
+  // handle with the inherit flag, with this object retaining ownership of the
+  // duplicated handle. As such, this object must live at least until after the
+  // watcher process has been created. Returns true on success, false on
+  // failure. This can fail if the call to DuplicateHandle fails. Each of this
+  // may only be called once.
+  bool SetOnInitializedEventHandle(HANDLE on_initialized_event_handle);
+  bool SetParentProcessHandle(HANDLE parent_process_handle_);
+
+  // Generates a command-line representing this configuration. Must be run from
+  // the main thread of the parent process.
+  base::CommandLine GenerateCommandLine();
+
+  // Appends all inherited handles to the provided vector. Does not clear the
+  // vector first.
+  void GetInheritedHandles(std::vector<HANDLE>* inherited_handles) const;
+
+ protected:
+  // Exposed for unittesting.
+
+  // Duplicate the provided |handle|, making it inheritable, and storing it in
+  // the provided |scoped_handle|. Also updated inherited_handles_.
+  bool SetHandle(HANDLE handle, base::win::ScopedHandle* scoped_handle);
+
+  base::FilePath chrome_exe_;
+
+  // Duplicated inheritable handles that are being shared from the parent to the
+  // child.
+  base::win::ScopedHandle on_initialized_event_handle_;
+  base::win::ScopedHandle parent_process_handle_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ChromeWatcherCommandLineGenerator);
+};
+
+// Class for processing a command-line used to start a Chrome Watcher process
+// and exposing the resulting configuration and any shared handles. To be used
+// within the watcher process.
+class ChromeWatcherCommandLine {
+ public:
+  // Causes the process to explode if any inherited handles weren't taken from
+  // this object.
+  ~ChromeWatcherCommandLine();
+
+  // Parses the provided command-line used to launch a Chrome Watcher process.
+  // If this fails any successfully opened handles will be closed prior to
+  // return. Returns a ChromeWatcherCommandLine object on success, nullptr
+  // otherwise.
+  static scoped_ptr<ChromeWatcherCommandLine> InterpretCommandLine(
+      const base::CommandLine& command_line);
+
+  // Accessors for handles. Any handles not taken from this object at the time
+  // of its destruction will cause a terminal error.
+  base::win::ScopedHandle& on_initialized_event_handle() {

[grt (UTC plus 2), 2015/12/22 16:31:31]

i like base::win::ScopedHandle TakeOnInitializedEventHandler() { return
std::move(on_initialized_event_handle_); } better since you can't accidentally
grab the ref to the ScopedHandle then destroy this instance, leading to badness.

[chrisha, 2015/12/23 14:08:23]

Sounds reasonable. I'll return to that.

+    return on_initialized_event_handle_;
+  }
+  base::win::ScopedHandle& parent_process_handle() {
+    return parent_process_handle_;
+  }
+
+  // Returns the ID of the main thread in the parent process.
+  DWORD main_thread_id() const { return main_thread_id_; }
+
+ private:
+  // Private constructor for use by InterpretCommandLine.
+  ChromeWatcherCommandLine(HANDLE on_initialized_event_handle,
+                           HANDLE parent_process_handle,
+                           DWORD main_thread_id);
+
+  base::win::ScopedHandle on_initialized_event_handle_;
+  base::win::ScopedHandle parent_process_handle_;
+
+  // The ID of the main thread in the parent process.
+  DWORD main_thread_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(ChromeWatcherCommandLine);
+};
 
 // Generates a CommandLine that will launch |chrome_exe| in Chrome Watcher mode
 // to observe |parent_process|, whose main thread is identified by