Add flow control between renderer and GPU processes, and, on Mac OS X,...

app/surface/accelerated_surface_mac.cc

Index: app/surface/accelerated_surface_mac.cc
===================================================================
--- app/surface/accelerated_surface_mac.cc	(revision 67289)
+++ app/surface/accelerated_surface_mac.cc	(working copy)
@@ -124,6 +124,8 @@
     glBindTexture(target, texture_);
     glTexParameteri(target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
     glTexParameteri(target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+    glTexParameteri(target, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
     // Generate and bind the framebuffer object.
     glGenFramebuffersEXT(1, &fbo_);
     glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo_);
@@ -220,6 +222,8 @@
     glBindTexture(target, texture_);
     glTexParameteri(target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
     glTexParameteri(target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+    glTexParameteri(target, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
   }
 
   // Allocate a new IOSurface, which is the GPU resource that can be