Fix depth texture sampling on compatibility profile.

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index a97879bdcc9443059501158ada04331afbb4e510..01995e28f8d8025b29359312fd925064bc18f09b 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -5239,10 +5239,15 @@ void GLES2DecoderImpl::DoBindTexture(GLenum target, GLuint client_id) {
       return;
     }
     LogClientServiceForInfo(texture, client_id, "glBindTexture");
+    glBindTexture(target, texture->service_id());
     if (texture->target() == 0) {
       texture_manager()->SetTarget(texture_ref, target);
+      if (!feature_info_->gl_version_info().BehavesLikeGLES()) {
+        // We only need to do it for DEPTH textures on GL with compatibility
+        // profile, but this is simpler.
+        glTexParameteri(target, GL_DEPTH_TEXTURE_MODE, GL_RED);
+      }

[piman, 2016/05/18 21:00:15]

Can you explain to me why this is needed and what issue it solves? This is way
far from obvious.

     }
-    glBindTexture(target, texture->service_id());
   } else {
     glBindTexture(target, 0);
   }