aura: Fix unit_tests on linux

ui/aura/desktop_host_linux.cc

Index: ui/aura/desktop_host_linux.cc
diff --git a/ui/aura/desktop_host_linux.cc b/ui/aura/desktop_host_linux.cc
index 7e9a5b110b073e12983307923cc62f8c27c31b27..3d6aef5dcf9deec1c063ce0469a65c20ab25706b 100644
--- a/ui/aura/desktop_host_linux.cc
+++ b/ui/aura/desktop_host_linux.cc
@@ -13,6 +13,7 @@
 #include <algorithm>
 
 #include "base/message_loop.h"
+#include "base/message_pump_observer.h"
 #include "base/message_pump_x.h"
 #include "ui/aura/cursor.h"
 #include "ui/aura/desktop.h"
@@ -222,7 +223,8 @@ bool ShouldSendCharEventForKeyboardCode(ui::KeyboardCode keycode) {
   }
 }
 
-class DesktopHostLinux : public DesktopHost {
+class DesktopHostLinux : public DesktopHost,
+                         public base::MessagePumpObserver {
  public:
   explicit DesktopHostLinux(const gfx::Rect& bounds);
   virtual ~DesktopHostLinux();
@@ -243,6 +245,12 @@ class DesktopHostLinux : public DesktopHost {
   virtual gfx::Point QueryMouseLocation() OVERRIDE;
   virtual void PostNativeEvent(const base::NativeEvent& event) OVERRIDE;
 
+  // base::MessagePumpObserver Overrides.
+  virtual base::EventStatus WillProcessEvent(
+      const base::NativeEvent& event) OVERRIDE;
+  virtual void DidProcessEvent(const base::NativeEvent& event) OVERRIDE;
+  virtual void OnMessagePumpDestroying() OVERRIDE;
+
   // Returns true if there's an X window manager present... in most cases.  Some
   // window managers (notably, ion3) don't implement enough of ICCCM for us to
   // detect that they're there.
@@ -287,6 +295,9 @@ DesktopHostLinux::DesktopHostLinux(const gfx::Rect& bounds)
   if (base::MessagePumpForUI::HasXInput2())
     ui::TouchFactory::GetInstance()->SetupXI2ForXWindow(xwindow_);
 #endif
+
+  base::MessagePumpX::SetDefaultDispatcher(this);
+  MessageLoopForUI::current()->AddObserver(this);
 }
 
 DesktopHostLinux::~DesktopHostLinux() {
@@ -294,6 +305,10 @@ DesktopHostLinux::~DesktopHostLinux() {
 
   // Clears XCursorCache.
   ui::GetXCursor(ui::kCursorClearXCursorCache);
+
+  base::MessagePumpX::SetDefaultDispatcher(NULL);
+  if (MessageLoop::current())
+    MessageLoopForUI::current()->RemoveObserver(this);
 }
 
 base::MessagePumpDispatcher::DispatchStatus DesktopHostLinux::Dispatch(
@@ -520,6 +535,18 @@ void DesktopHostLinux::PostNativeEvent(const base::NativeEvent& native_event) {
   XSendEvent(xdisplay_, xwindow_, False, 0, &xevent);
 }
 
+base::EventStatus DesktopHostLinux::WillProcessEvent(
+    const base::NativeEvent& event) {
+  return base::EVENT_CONTINUE;
+}
+
+void DesktopHostLinux::DidProcessEvent(const base::NativeEvent& event) {
+}
+
+void DesktopHostLinux::OnMessagePumpDestroying() {
+  desktop_->DeleteInstance();
+}
+
 bool DesktopHostLinux::IsWindowManagerPresent() {
   // Per ICCCM 2.8, "Manager Selections", window managers should take ownership
   // of WM_Sn selections (where n is a screen number).