Bug 803299 - Respect gfx.android.rgb16.force pref. r=blassey

mobile/android/app/mobile.js

@@ -357,6 +357,9 @@ pref("gfx.displayport.strategy_vb.danger_y_incr", -1); // additional danger zone
 // prediction bias strategy options
 pref("gfx.displayport.strategy_pb.threshold", -1); // velocity threshold in inches/frame
 
+// Allow 24-bit colour when the hardware supports it
+pref("gfx.android.rgb16.force", false);
+
 // don't allow JS to move and resize existing windows
 pref("dom.disable_window_move_resize", true);
 

mobile/android/base/GeckoApp.java

@@ -2191,6 +2191,15 @@ abstract public class GeckoApp
     }
 
     protected void connectGeckoLayerClient() {
+        // See if we want to force 16-bit colour before doing anything
+        PrefsHelper.getPref("gfx.android.rgb16.force", new PrefsHelper.PrefHandlerBase() {
+            @Override public void prefValue(String pref, boolean force16bit) {
+                if (force16bit) {
+                    GeckoAppShell.setScreenDepthOverride(16);
+                }
+            }
+        });
+
         mLayerView.getLayerClient().notifyGeckoReady();
 
         mLayerView.addTouchInterceptor(this);

mobile/android/base/GeckoAppShell.java

@@ -1385,7 +1385,7 @@ public class GeckoAppShell
      * Returns the colour depth of the default screen. This will either be
      * 24 or 16.
      */
-    public static int getScreenDepth() {
+    public static synchronized int getScreenDepth() {
         if (sScreenDepth == 0 && getGeckoInterface() != null) {
             switch (getGeckoInterface().getActivity().getWindowManager().getDefaultDisplay().getPixelFormat()) {
             case PixelFormat.RGBA_8888 :
@@ -1402,6 +1402,15 @@ public class GeckoAppShell
         return sScreenDepth;
     }
 
+    public static synchronized void setScreenDepthOverride(int aScreenDepth) {
+        if (sScreenDepth != 0) {
+            Log.e(LOGTAG, "Tried to override screen depth after it's already been set");
+            return;
+        }
+
+        sScreenDepth = aScreenDepth;
+    }
+
     public static void setFullScreen(boolean fullscreen) {
         if (getGeckoInterface() != null)
             getGeckoInterface().setFullScreen(fullscreen);