Bug 937204 - 1/3. Simplify the D3D9_LAYERS gfxinfo check and only run it on Windows - r=jrmuizel

gfx/thebes/gfxPlatform.cpp

@@ -2030,7 +2030,7 @@ static bool sPrefLayersAccelerationForceEnabled = false;
 static bool sPrefLayersAccelerationDisabled = false;
 static bool sPrefLayersPreferOpenGL = false;
 static bool sPrefLayersPreferD3D9 = false;
-static bool sLayersSupportsD3D9 = true;
+static bool sLayersSupportsD3D9 = false;
 static int  sPrefLayoutFrameRate = -1;
 static bool sBufferRotationEnabled = false;
 static bool sComponentAlphaEnabled = true;
@@ -2055,15 +2055,21 @@ InitLayersAccelerationPrefs()
     sComponentAlphaEnabled = Preferences::GetBool("layers.componentalpha.enabled", true);
     sPrefBrowserTabsRemote = Preferences::GetBool("browser.tabs.remote", false);
 
-    nsCOMPtr<nsIGfxInfo> gfxInfo = do_GetService("@mozilla.org/gfx/info;1");
-    if (gfxInfo) {
-      int32_t status;
-      if (NS_SUCCEEDED(gfxInfo->GetFeatureStatus(nsIGfxInfo::FEATURE_DIRECT3D_9_LAYERS, &status))) {
-        if (status != nsIGfxInfo::FEATURE_NO_INFO && !sPrefLayersAccelerationForceEnabled) {
-          sLayersSupportsD3D9 = false;
+#ifdef XP_WIN
+    if (sPrefLayersAccelerationForceEnabled) {
+      sLayersSupportsD3D9 = true;
+    } else {
+      nsCOMPtr<nsIGfxInfo> gfxInfo = do_GetService("@mozilla.org/gfx/info;1");
+      if (gfxInfo) {
+        int32_t status;
+        if (NS_SUCCEEDED(gfxInfo->GetFeatureStatus(nsIGfxInfo::FEATURE_DIRECT3D_9_LAYERS, &status))) {
+          if (status == nsIGfxInfo::FEATURE_NO_INFO) {
+            sLayersSupportsD3D9 = true;
+          }
         }
       }
     }
+#endif
 
     sLayersAccelerationPrefsInitialized = true;
   }