Add CommitOverlayPlanesCHROMIUM command buffer function

gpu/GLES2/extensions/CHROMIUM/CHROMIUM_commit_overlay_planes.txt

+Name
+
+    CHROMIUM_commit_overlay_planes
+
+Name Strings
+
+    GL_CHROMIUM_commit_overlay_planes
+
+Version
+
+    Last Modified Date: Nov 23, 2015
+
+Dependencies
+
+    OpenGL ES 2.0 is required.
+
+Overview
+
+    This extension allows a client to request the display of hardware overlay
+    planes that have been scheduled with glScheduleOverlayPlaneCHROMIUM since
+    the last call to glSwapBuffers, glPostSubBufferCHROMIUM, or
+    glCommitOverlayPlanesCHROMIUM. This allows a client to display overlay
+    planes without swapping the framebuffer.
+
+    Issues
+
+    None
+
+New Tokens
+
+    None
+
+New Procedures and Functions
+
+    The command
+
+        glCommitOverlayPlanesCHROMIUM ();
+
+    Displays the scheduled overlay planes.
+
+Errors
+
+    None.
+
+New State
+
+    None.