aura/chromeos: Avoid suspending while video is playing.

This adds an ash::VideoDetector class that watches for layer
updates and attempts to detect the playback of video.  A
Chrome OS-specific observer updates a _CHROME_VIDEO_TIME
property on the X root window, which is used by the power
manager to defer screen dimming or other power management
features.  This matches the implementation currently in use
on Chrome OS, with Chrome taking the X window manager's role
for detecting video and setting the property.

BUG=110114
TEST=added; also manually checked that the property is updated


Review URL: http://codereview.chromium.org/9249004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@118171 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 45 insertions, 0 deletions

diff --git a/ui/base/x/x11_util.cc b/ui/base/x/x11_util.cc
index 9605fde..302ffd6 100644
--- a/ui/base/x/x11_util.cc
+++ b/ui/base/x/x11_util.cc
@@ -18,6 +18,7 @@
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/memory/singleton.h"
 #include "base/message_loop.h"
 #include "base/string_number_conversions.h"
@@ -514,11 +515,46 @@ bool GetStringProperty(
   return true;
 }
 
+bool SetIntProperty(XID window,
+                    const std::string& name,
+                    const std::string& type,
+                    int value) {
+  std::vector<int> values(1, value);
+  return SetIntArrayProperty(window, name, type, values);
+}
+
+bool SetIntArrayProperty(XID window,
+                         const std::string& name,
+                         const std::string& type,
+                         const std::vector<int>& value) {
+  DCHECK(!value.empty());
+  Atom name_atom = GetAtom(name.c_str());
+  Atom type_atom = GetAtom(type.c_str());
+
+  // XChangeProperty() expects values of type 32 to be longs.
+  scoped_array<long> data(new long[value.size()]);
+  for (size_t i = 0; i < value.size(); ++i)
+    data[i] = value[i];
+
+  gdk_error_trap_push();
+  XChangeProperty(ui::GetXDisplay(),
+                  window,
+                  name_atom,
+                  type_atom,
+                  32,  // size in bits of items in 'value'
+                  PropModeReplace,
+                  reinterpret_cast<const unsigned char*>(data.get()),
+                  value.size());  // num items
+  XSync(ui::GetXDisplay(), False);
+  return gdk_error_trap_pop() == 0;
+}
+
 Atom GetAtom(const char* name) {
 #if defined(TOOLKIT_USES_GTK)
   return gdk_x11_get_xatom_by_name_for_display(
       gdk_display_get_default(), name);
 #else
+  // TODO(derat): Cache atoms to avoid round-trips to the server.
   return XInternAtom(GetXDisplay(), name, false);
 #endif
 }
diff --git a/ui/base/x/x11_util.h b/ui/base/x/x11_util.h
index 757b149..411c941 100644
--- a/ui/base/x/x11_util.h
+++ b/ui/base/x/x11_util.h
@@ -124,6 +124,15 @@ UI_EXPORT bool GetAtomArrayProperty(XID window,
 UI_EXPORT bool GetStringProperty(
     XID window, const std::string& property_name, std::string* value);
 
+UI_EXPORT bool SetIntProperty(XID window,
+                              const std::string& name,
+                              const std::string& type,
+                              int value);
+UI_EXPORT bool SetIntArrayProperty(XID window,
+                                   const std::string& name,
+                                   const std::string& type,
+                                   const std::vector<int>& value);
+
 // Gets the X atom for default display corresponding to atom_name.
 Atom GetAtom(const char* atom_name);