Add missing GL extension check in SharedContextRateLimiter

This bug was unmasked by this CL that re-enabled overdraw
optimizations in GPU-accelerated 2D canvas:
https://chromium-review.googlesource.com/c/chromium/src/+/800750

Crash happens on configuration that do not support the sync query
extension.

BUG=791608

Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: I0da7be2f305d61881ba57d999329de2864d68ca5
Reviewed-on: https://chromium-review.googlesource.com/806678Reviewed-by: Olivia Lai <xlai@chromium.org>
Commit-Queue: Justin Novosad <junov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521466}

third_party/WebKit/Source/platform/graphics/gpu/SharedContextRateLimiter.cpp

@@ -46,9 +46,8 @@ void SharedContextRateLimiter::Tick() {
     return;
 
   queries_.push_back(0);
-  if (can_use_sync_queries_)
-    gl->GenQueriesEXT(1, &queries_.back());
   if (can_use_sync_queries_) {
+    gl->GenQueriesEXT(1, &queries_.back());
     gl->BeginQueryEXT(GL_COMMANDS_COMPLETED_CHROMIUM, queries_.back());
     gl->EndQueryEXT(GL_COMMANDS_COMPLETED_CHROMIUM);
   }
@@ -70,7 +69,8 @@ void SharedContextRateLimiter::Reset() {
     return;
 
   gpu::gles2::GLES2Interface* gl = context_provider_->ContextGL();
-  if (gl && gl->GetGraphicsResetStatusKHR() == GL_NO_ERROR) {
+  if (can_use_sync_queries_ && gl &&
+      gl->GetGraphicsResetStatusKHR() == GL_NO_ERROR) {
     while (queries_.size() > 0) {
       gl->DeleteQueriesEXT(1, &queries_.front());
       queries_.pop_front();