In WinAura, also kill the Metro viewer process in AttemptExit().

chrome/browser/browser_process_platform_part_winaura.cc

Index: chrome/browser/browser_process_platform_part_winaura.cc
diff --git a/chrome/browser/browser_process_platform_part_winaura.cc b/chrome/browser/browser_process_platform_part_winaura.cc
index d1ca40c958a1385680946824c042e7999272b6d6..abee0994c6498ca735b446303064fbd7508f2fad 100644
--- a/chrome/browser/browser_process_platform_part_winaura.cc
+++ b/chrome/browser/browser_process_platform_part_winaura.cc
@@ -5,6 +5,8 @@
 #include "chrome/browser/browser_process_platform_part_winaura.h"
 
 #include "base/command_line.h"
+#include "base/logging.h"
+#include "base/process_util.h"
 #include "chrome/browser/metro_viewer/metro_viewer_process_host_win.h"
 #include "chrome/common/chrome_switches.h"
 
@@ -29,5 +31,19 @@ void BrowserProcessPlatformPart::StartTearDown() {
 }
 
 void BrowserProcessPlatformPart::OnMetroViewerProcessTerminated() {
-  metro_viewer_process_host_.reset(NULL);
+  metro_viewer_process_host_.reset();
+}
+
+void BrowserProcessPlatformPart::TerminateMetroViewerProcess() {
+  if (metro_viewer_process_host_) {
+    base::ProcessId viewer_id =
+        metro_viewer_process_host_->GetViewerProcessId();
+    if (viewer_id == base::kNullProcessId)
+      return;
+    // The viewer doesn't hold any state so it is fine to kill it before it
+    // cleanly exits. This will trigger MetroViewerProcessHost::OnChannelError()
+    // which will cleanup references to g_browser_process.
+    bool success = base::KillProcessById(viewer_id, 0, true);
+    DCHECK(success);
+  }
 }