Issue #1360 - Part 1: Simplify layers acceleration prefs.

This gets rid of platform-dependent hard-coded defaults, but keeps
build-time blocking if there is no GL provider (in which case layers
acceleration almost certainly won't work because it needs a GL
compositor and would likely crash without)

New prefs are
- layers.acceleration.enabled to enable HWA
- layers.acceleration.force to force it enabled (requires .enabled to be
  set as well)

This is the platform part of this issue. The rest will be front-end work
(Preference UI integration and pref migration)

1 files changed, 4 insertions, 37 deletions

diff --git a/gfx/thebes/gfxPlatform.cpp b/gfx/thebes/gfxPlatform.cpp
index 50d1fcb46..4cd044f90 100644
--- a/gfx/thebes/gfxPlatform.cpp
+++ b/gfx/thebes/gfxPlatform.cpp
@@ -571,40 +571,6 @@ gfxPlatform::Init()
       }
     }
 
-    // Drop a note in the crash report if we end up forcing an option that could
-    // destabilize things.  New items should be appended at the end (of an existing
-    // or in a new section), so that we don't have to know the version to interpret
-    // these cryptic strings.
-    {
-      nsAutoCString forcedPrefs;
-      // D2D prefs
-      forcedPrefs.AppendPrintf("FP(D%d%d",
-                               gfxPrefs::Direct2DDisabled(),
-                               gfxPrefs::Direct2DForceEnabled());
-      // Layers prefs
-      forcedPrefs.AppendPrintf("-L%d%d%d%d",
-                               gfxPrefs::LayersAMDSwitchableGfxEnabled(),
-                               gfxPrefs::LayersAccelerationDisabledDoNotUseDirectly(),
-                               gfxPrefs::LayersAccelerationForceEnabledDoNotUseDirectly(),
-                               gfxPrefs::LayersD3D11ForceWARP());
-      // WebGL prefs
-      forcedPrefs.AppendPrintf("-W%d%d%d%d%d%d%d%d",
-                               gfxPrefs::WebGLANGLEForceD3D11(),
-                               gfxPrefs::WebGLANGLEForceWARP(),
-                               gfxPrefs::WebGLDisabled(),
-                               gfxPrefs::WebGLDisableANGLE(),
-                               gfxPrefs::WebGLDXGLEnabled(),
-                               gfxPrefs::WebGLForceEnabled(),
-                               gfxPrefs::WebGLForceLayersReadback(),
-                               gfxPrefs::WebGLForceMSAA());
-      // Prefs that don't fit into any of the other sections
-      forcedPrefs.AppendPrintf("-T%d%d%d%d) ",
-                               gfxPrefs::AndroidRGB16Force(),
-                               gfxPrefs::CanvasAzureAccelerated(),
-                               gfxPrefs::DisableGralloc(),
-                               gfxPrefs::ForceShmemTiles());
-    }
-
     InitMoz2DLogging();
 
     gGfxPlatformPrefsLock = new Mutex("gfxPlatform::gGfxPlatformPrefsLock");
@@ -2171,7 +2137,7 @@ gfxPlatform::InitCompositorAccelerationPrefs()
                          FeatureStatus::Blocked,
                          "Acceleration blocked by platform"))
   {
-    if (gfxPrefs::LayersAccelerationDisabledDoNotUseDirectly()) {
+    if (!gfxPrefs::LayersAccelerationEnabledDoNotUseDirectly()) {
       feature.UserDisable("Disabled by pref",
                           NS_LITERAL_CSTRING("FEATURE_FAILURE_COMP_PREF"));
     } else if (acceleratedEnv && *acceleratedEnv == '0') {
@@ -2185,8 +2151,9 @@ gfxPlatform::InitCompositorAccelerationPrefs()
   }
 
   // This has specific meaning elsewhere, so we always record it.
-  if (gfxPrefs::LayersAccelerationForceEnabledDoNotUseDirectly()) {
-    feature.UserForceEnable("Force-enabled by pref");
+  if (gfxPrefs::LayersAccelerationEnabledDoNotUseDirectly() &&
+      gfxPrefs::LayersAccelerationForceEnabledDoNotUseDirectly()) {
+    feature.UserForceEnable("Force-enabled by prefs");
   }
 
   // Safe mode trumps everything.