Blacklist partial swaps on linux

ui/gl/gl_surface_x11.cc

Index: ui/gl/gl_surface_x11.cc
diff --git a/ui/gl/gl_surface_x11.cc b/ui/gl/gl_surface_x11.cc
index 54c7f438829c13d5132500de38dc00b5eca9ee15..cde04f1db9b0c660d9745b25899c7f829e9ce9bd 100644
--- a/ui/gl/gl_surface_x11.cc
+++ b/ui/gl/gl_surface_x11.cc
@@ -32,7 +32,7 @@ class NativeViewGLSurfaceOSMesa : public GLSurfaceOSMesa {
   virtual bool Resize(const gfx::Size& new_size) OVERRIDE;
   virtual bool IsOffscreen() OVERRIDE;
   virtual bool SwapBuffers() OVERRIDE;
-  virtual std::string GetExtensions() OVERRIDE;
+  virtual bool SupportsPostSubBuffer() OVERRIDE;
   virtual bool PostSubBuffer(int x, int y, int width, int height) OVERRIDE;
 
  protected:
@@ -218,11 +218,8 @@ bool NativeViewGLSurfaceOSMesa::SwapBuffers() {
   return true;
 }
 
-std::string NativeViewGLSurfaceOSMesa::GetExtensions() {
-  std::string extensions = gfx::GLSurfaceOSMesa::GetExtensions();
-  extensions += extensions.empty() ? "" : " ";
-  extensions += "GL_CHROMIUM_post_sub_buffer";
-  return extensions;
+bool NativeViewGLSurfaceOSMesa::SupportsPostSubBuffer() {
+  return true;
 }
 
 bool NativeViewGLSurfaceOSMesa::PostSubBuffer(