Implement OverlayPanels as SceneOverlays

chrome/android/java/src/org/chromium/chrome/browser/compositor/scene_layer/ContextualSearchSceneLayer.java

Index: chrome/android/java/src/org/chromium/chrome/browser/compositor/scene_layer/ContextualSearchSceneLayer.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/compositor/scene_layer/ContextualSearchSceneLayer.java b/chrome/android/java/src/org/chromium/chrome/browser/compositor/scene_layer/ContextualSearchSceneLayer.java
index df3a5811d30c8ac17afa9c932212f332f7556837..a68dae93d0752d1fa0475c55ff08637afe34741a 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/compositor/scene_layer/ContextualSearchSceneLayer.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/compositor/scene_layer/ContextualSearchSceneLayer.java
@@ -18,12 +18,15 @@ import org.chromium.ui.resources.ResourceManager;
  * A SceneLayer to render layers for ContextualSearchLayout.
  */
 @JNINamespace("chrome::android")
-public class ContextualSearchSceneLayer extends SceneLayer {
+public class ContextualSearchSceneLayer extends SceneOverlayLayer {
 
     // NOTE: If you use SceneLayer's native pointer here, the JNI generator will try to
     // downcast using reinterpret_cast<>. We keep a separate pointer to avoid it.
     private long mNativePtr;
 
+    /** If the scene layer has been initialized. */
+    private boolean mIsInitialized;
+
     private final float mDpToPx;
 
     public ContextualSearchSceneLayer(float dpToPx) {
@@ -44,6 +47,13 @@ public class ContextualSearchSceneLayer extends SceneLayer {
             ContextualSearchPeekPromoControl peekPromoControl,
             ContextualSearchPromoControl promoControl,
             ContextualSearchIconSpriteControl spriteControl) {
+        if (!mIsInitialized && resourceManager != null) {
+            nativeCreateContextualSearchLayer(mNativePtr, resourceManager);

[pedro (no code reviews), 2016/05/04 22:59:34]

Can we only create the layer when it becomes visible?

[mdjones, 2016/05/05 00:46:20]

With the follow-up change, that will be the case.

[pedro (no code reviews), 2016/05/05 01:40:52]

The follow-up change will prevent this update() method from being called.

What I'm asking is, even if this method gets called, why would we create the
layer if the panel is not visible?

In other words, can't we just move the if block to right after the early return
below?

[mdjones, 2016/05/05 17:48:34]

Unfortunately, no. The scene layer needs to exist in order for the content tree
to be added to it (otherwise we just get a white screen). 

[pedro (no code reviews), 2016/05/05 19:12:15]

I'm asking to not create the *ContextualSearch* layer and you're saying that
can't do that because you need the *Scene* layer?

But, you need the *Scene* layer just because you're adding it to the hierarchy
even when you don't need it?

Anyway, it should still be possible to not create the *ContextualSearch* layer,
even when we are unnecessarily adding *Scene* layer to the hierarchy because the
Content tree will be added to the Content layer, not the *ContextualSearch*
layer.

[mdjones, 2016/05/05 20:46:02]

Yes, because at this level, the two are indistinguishable. Again, I'm using the
current infrastructure to build this, I address this in follow-up changes. But
just to be clear, we only ever create one of these and having hidden layers has
virtually no affect on rendering speed.

+            mIsInitialized = true;
+        }
+
+        // Don't try to update the layer if not initialized or showing.
+        if (!mIsInitialized || !panel.isShowing()) return;
 
         int searchContextViewId = searchBarControl.getSearchContextViewId();
         int searchTermViewId = searchBarControl.getSearchTermViewId();
@@ -110,6 +120,8 @@ public class ContextualSearchSceneLayer extends SceneLayer {
                 R.drawable.contextual_search_promo_ripple,
                 searchPeekPromoTextViewId,
                 mDpToPx,
+                panel.getBasePageBrightness(),
+                panel.getBasePageY() * mDpToPx,
                 panel.getContentViewCore(),
                 searchPromoVisible,
                 searchPromoHeightPx,
@@ -141,8 +153,19 @@ public class ContextualSearchSceneLayer extends SceneLayer {
                 isProgressBarVisible,
                 progressBarHeight * mDpToPx,
                 progressBarOpacity,
-                progressBarCompletion,
-                resourceManager);
+                progressBarCompletion);
+    }
+
+    @Override
+    public void setContentTree(SceneLayer contentTree) {
+        nativeSetContentTree(mNativePtr, contentTree);
+    }
+
+    /**
+     * Hide the layer tree; for use if the panel is not being shown.
+     */
+    public void hideTree() {
+        nativeHideTree(mNativePtr);
     }
 
     @Override
@@ -159,10 +182,19 @@ public class ContextualSearchSceneLayer extends SceneLayer {
     @Override
     public void destroy() {
         super.destroy();
+        mIsInitialized = false;
         mNativePtr = 0;
     }
 
     private native long nativeInit();
+    private native void nativeCreateContextualSearchLayer(
+            long nativeContextualSearchSceneLayer,
+            ResourceManager resourceManager);
+    private native void nativeSetContentTree(
+            long nativeContextualSearchSceneLayer,
+            SceneLayer contentTree);
+    private native void nativeHideTree(
+            long nativeContextualSearchSceneLayer);
     private native void nativeUpdateContextualSearchLayer(
             long nativeContextualSearchSceneLayer,
             int searchBarBackgroundResourceId,
@@ -180,6 +212,8 @@ public class ContextualSearchSceneLayer extends SceneLayer {
             int peekPromoRippleResourceId,
             int peekPromoTextResourceId,
             float dpToPx,
+            float basePageBrightness,
+            float basePageYOffset,
             ContentViewCore contentViewCore,
             boolean searchPromoVisible,
             float searchPromoHeight,
@@ -211,6 +245,5 @@ public class ContextualSearchSceneLayer extends SceneLayer {
             boolean isProgressBarVisible,
             float progressBarHeight,
             float progressBarOpacity,
-            int progressBarCompletion,
-            ResourceManager resourceManager);
+            int progressBarCompletion);
 }