cc: Implement deadine scheduling disabled by default

cc/base/switches.cc

Index: cc/base/switches.cc
diff --git a/cc/base/switches.cc b/cc/base/switches.cc
index 3fc43029c266cd1666695f7a90dc110953523bf7..3fa40e916ed91dc7793e3895b16df35b707d166e 100644
--- a/cc/base/switches.cc
+++ b/cc/base/switches.cc
@@ -27,6 +27,16 @@ const char kDisableImplSidePainting[] = "disable-impl-side-painting";
 // Paint content on the compositor thread instead of the main thread.
 const char kEnableImplSidePainting[] = "enable-impl-side-painting";
 
+// Disables the deadline scheduler.
+// Overrides the kEnableDeadlineScheduling flag.
+const char kDisableDeadlineScheduling[] = "disable-deadline-scheduling";
+
+// Deadline scheduling gives children compositors and the main thread an
+// interval over which they can produce content instead of always consuming
+// their input on the next BeginFrame. This allows a total pipeline latency
+// of less than 1 vsync if their intervals are properly nested.
+const char kEnableDeadlineScheduling[] = "enable-deadline-scheduling";
+
 const char kEnableTopControlsPositionCalculation[] =
     "enable-top-controls-position-calculation";
 
@@ -161,5 +171,20 @@ bool IsMapImageEnabled() {
   return false;
 }
 
+bool IsDeadlineSchedulingEnabled() {
+  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+
+  if (command_line.HasSwitch(cc::switches::kDisableDeadlineScheduling))
+    return false;
+  else if (command_line.HasSwitch(cc::switches::kEnableDeadlineScheduling))
+    return true;
+
+#if defined(OS_ANDROID)
+  return true;
+#else
+  return false;
+#endif
+}
+
 }  // namespace switches
 }  // namespace cc