gpu: Add EGL fence support.

ui/gl/gl_surface_egl.h

Index: ui/gl/gl_surface_egl.h
diff --git a/ui/gl/gl_surface_egl.h b/ui/gl/gl_surface_egl.h
index 17e6e9404ceb9fda2c1542d76bb968f9e2ade879..f70d0573b651b139fd7d98431f39312cdc4cd835 100644
--- a/ui/gl/gl_surface_egl.h
+++ b/ui/gl/gl_surface_egl.h
@@ -67,6 +67,7 @@ class GL_EXPORT NativeViewGLSurfaceEGL : public GLSurfaceEGL {
   virtual std::string GetExtensions() OVERRIDE;
   virtual bool PostSubBuffer(int x, int y, int width, int height) OVERRIDE;
   virtual VSyncProvider* GetVSyncProvider() OVERRIDE;
+  virtual void SetMaximumFrameLatency(unsigned int frames) OVERRIDE;

[Sami, 2013/04/24 10:44:18]

We spoke with Daniel that maybe something like SetMaximumPendingSwaps would be a
better name for this since that's also used elsewhere in the code and the
current name sounds like this gives a hard guarantee when it doesn't really know
what's happening downstream.

[no sievers, 2013/04/24 12:23:53]

In gles2_implementation.cc we call it 'MaxSwapBuffers'.  

[epennerAtGoogle, 2013/04/24 19:33:38]

Okay. I stole this name from D3D :P  I'll rename.

 
  protected:
   virtual ~NativeViewGLSurfaceEGL();
@@ -78,6 +79,9 @@ class GL_EXPORT NativeViewGLSurfaceEGL : public GLSurfaceEGL {
   bool supports_post_sub_buffer_;
   EGLConfig config_;
 
+  std::deque<EGLSyncKHR> frame_fences_;
+  unsigned int max_frame_latency_;
+
   scoped_ptr<VSyncProvider> vsync_provider_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeViewGLSurfaceEGL);