Make GrGLGetDriverInfo work for null strings.

The media unit tests in Chromium use a test context that returns nullptr for its vendor/renderer strings.

TBR=robertphillips@google.com

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1831633002

Review URL: https://codereview.chromium.org/1831633002

1 files changed, 8 insertions, 0 deletions

diff --git a/src/gpu/gl/GrGLUtil.cpp b/src/gpu/gl/GrGLUtil.cpp
index b5e5855401..c766f13c56 100644
--- a/src/gpu/gl/GrGLUtil.cpp
+++ b/src/gpu/gl/GrGLUtil.cpp
@@ -102,6 +102,14 @@ void GrGLGetDriverInfo(GrGLStandard standard,
 
     *outDriver = kUnknown_GrGLDriver;
     *outVersion = GR_GL_DRIVER_UNKNOWN_VER;
+    // These null checks are for test GL contexts that return nullptr in their
+    // glGetString implementation.
+    if (!rendererString) {
+        rendererString = "";
+    }
+    if (!versionString) {
+        versionString = "";
+    }
 
     if (0 == strcmp(rendererString, "Chromium")) {
         *outDriver = kChromium_GrGLDriver;