Added ability to force a GLContext SwapInterval to zero.

ui/gl/gl_context.cc

Index: ui/gl/gl_context.cc
diff --git a/ui/gl/gl_context.cc b/ui/gl/gl_context.cc
index e35806917f3e15cbc87f77124a8fa4c73d850e80..71a54c4d89e27bc09c8de85956d7bf71e549691e 100644
--- a/ui/gl/gl_context.cc
+++ b/ui/gl/gl_context.cc
@@ -52,7 +52,10 @@ bool GLContext::FlushEvent::IsSignaled() {
   return flag_.IsSet();
 }
 
-GLContext::GLContext(GLShareGroup* share_group) : share_group_(share_group) {
+GLContext::GLContext(GLShareGroup* share_group) :
+    share_group_(share_group),
+    swap_interval(1),
+    force_swap_interval_zero(false) {
   if (!share_group_.get())
     share_group_ = new GLShareGroup;
 
@@ -178,6 +181,16 @@ void GLContext::SetGLStateRestorer(GLStateRestorer* state_restorer) {
   state_restorer_ = make_scoped_ptr(state_restorer);
 }
 
+void GLContext::SetSwapInterval(int interval) {
+  swap_interval = interval;
+  OnSetSwapInterval(force_swap_interval_zero ? 0 : swap_interval);
+}
+
+void GLContext::ForceSwapIntervalZero(bool force) {
+  force_swap_interval_zero = force;
+  OnSetSwapInterval(force_swap_interval_zero ? 0 : swap_interval);
+}
+
 bool GLContext::WasAllocatedUsingRobustnessExtension() {
   return false;
 }