GLRenderer: only disable shared images on Android

Shared images are necessary to implement WebGPU on Mac, make sure they
are disabled only on the platform that requires them disabled.

BUG=chromium:900963
BUG=chromium:877147

Change-Id: Ie588d40e5e2d38b57037422c4dd04213617f20eb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1579979Reviewed-by: Eric Karl <ericrk@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653518}

components/viz/service/display/display.h

@@ -81,9 +81,14 @@ class VIZ_SERVICE_EXPORT Display : public DisplaySchedulerClient,
 
   // TODO(cblume, crbug.com/900973): |enable_shared_images| is a temporary
   // solution that unblocks us until SharedImages are threadsafe in WebView.
+#if defined(ANDROID)
+  static constexpr bool kEnableSharedImages = false;
+#else
+  static constexpr bool kEnableSharedImages = true;
+#endif
   void Initialize(DisplayClient* client,
                   SurfaceManager* surface_manager,
-                  bool enable_shared_images = false);
+                  bool enable_shared_images = kEnableSharedImages);
 
   void AddObserver(DisplayObserver* observer);
   void RemoveObserver(DisplayObserver* observer);