DCHECK if shader compilation fails that it's due to context loss.

cc/test/test_gles2_interface.cc

Index: cc/test/test_gles2_interface.cc
diff --git a/cc/test/test_gles2_interface.cc b/cc/test/test_gles2_interface.cc
index 6ce087fe222e7579787a4ef373e4d63bd4164700..c1a26fad9c12679b8176d53ea666ae8011020ac1 100644
--- a/cc/test/test_gles2_interface.cc
+++ b/cc/test/test_gles2_interface.cc
@@ -423,4 +423,8 @@ void TestGLES2Interface::LoseContextCHROMIUM(GLenum current, GLenum other) {
   test_context_->loseContextCHROMIUM(current, other);
 }
 
+GLboolean TestGLES2Interface::IsContextLost() {
+  return test_context_->isContextLost();
+}
+
 }  // namespace cc