Fix blue flashes on Mac

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 6121a58da44ff4784a8c609b3c3e305337fbc57d..45d0f8465a279cb5abac0aa10b0d0ef0b0db5f05 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -2482,9 +2482,6 @@ bool GLES2DecoderImpl::Initialize(
     DoBindFramebuffer(GL_FRAMEBUFFER, 0);
   }
 
-  // Clear the backbuffer.
-  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
-
   // OpenGL ES 2.0 implicitly enables the desktop GL capability
   // VERTEX_PROGRAM_POINT_SIZE and doesn't expose this enum. This fact
   // isn't well documented; it was discovered in the Khronos OpenGL ES
@@ -2528,6 +2525,9 @@ bool GLES2DecoderImpl::Initialize(
   DoBindFramebuffer(GL_FRAMEBUFFER, 0);
   DoBindRenderbuffer(GL_RENDERBUFFER, 0);
 
+  // Clear the backbuffer.
+  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
+
   if (feature_info_->workarounds().reverse_point_sprite_coord_origin) {
     glPointParameteri(GL_POINT_SPRITE_COORD_ORIGIN, GL_LOWER_LEFT);
   }