Define a --force-gpu-rasterization flag

cc/trees/layer_tree_settings.h

Index: cc/trees/layer_tree_settings.h
diff --git a/cc/trees/layer_tree_settings.h b/cc/trees/layer_tree_settings.h
index 0a48b474988bf81767fae11b2b33eedc9f5f632f..4ebcb5c64b3eded97030810a3fdd1085a5fc2fab 100644
--- a/cc/trees/layer_tree_settings.h
+++ b/cc/trees/layer_tree_settings.h
@@ -30,7 +30,12 @@ class CC_EXPORT LayerTreeSettings {
   bool show_overdraw_in_tracing;
   bool can_use_lcd_text;
   bool should_clear_root_render_pass;
-  bool gpu_rasterization;
+  enum GpuRasterizationState {
+    GpuRasterizationDisabled,
+    GpuRasterizationEnabled,

[nduca, 2014/03/08 04:18:02]

Once you get into cc, you can use sw/hw/forced so that its clear what mode we're
in. That part of the previous review discussion seemed solid.

[ernstm, 2014/03/08 05:13:53]

In the previous review we settled on cpu/hybrid/gpu.

[ajuma, 2014/03/08 19:04:02]

Switched cc back to using cpu/hybrid/gpu.

+    GpuRasterizationForced,
+  };
+  GpuRasterizationState gpu_rasterization_state;
 
   enum ScrollbarAnimator {
     NoAnimator,