When possible, draw the toolbar shadow with the compositor

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

Index: chrome/android/java/src/org/chromium/chrome/browser/compositor/scene_layer/TabListSceneLayer.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/compositor/scene_layer/TabListSceneLayer.java b/chrome/android/java/src/org/chromium/chrome/browser/compositor/scene_layer/TabListSceneLayer.java
index 6415820c0f4fc388a036f13d87e208498b4bc16f..0938b0feae3fd0500aa698b9fc9b7a4239890d83 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/compositor/scene_layer/TabListSceneLayer.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/compositor/scene_layer/TabListSceneLayer.java
@@ -73,8 +73,14 @@ public class TabListSceneLayer extends SceneLayer {
 
             int borderColorResource =
                     t.isIncognito() ? R.color.tab_back_incognito : R.color.tab_back;
+
+            // Do not show the toolbar shadow if exiting the tab switcher to a native page.
+            boolean needsToolbarShadow =
+                    t.needsToolbarShadow() || (t.isNativePage() && t.getToolbarAlpha() < 1.0f);
+
             // TODO(dtrainor, clholgat): remove "* dpToPx" once the native part fully supports dp.
             nativePutTabLayer(mNativePtr, t.getId(), R.id.control_container,
+                    R.drawable.toolbar_shadow,
                     R.drawable.btn_tab_close,
                     R.drawable.tabswitcher_border_frame_shadow,
                     R.drawable.tabswitcher_border_frame_decoration, R.drawable.logo_card_back,
@@ -98,7 +104,7 @@ public class TabListSceneLayer extends SceneLayer {
                     defaultThemeColor, t.getToolbarBackgroundColor(), closeButtonColor,
                     t.anonymizeToolbar(), R.drawable.textbox, t.getTextBoxBackgroundColor(),
                     t.getTextBoxAlpha(), t.getToolbarAlpha(), t.getToolbarYOffset() * dpToPx,
-                    t.getSideBorderScale(), true, t.insetBorderVertical());
+                    t.getSideBorderScale(), true, t.insetBorderVertical(), needsToolbarShadow);
         }
         nativeFinishBuildingFrame(mNativePtr);
     }
@@ -136,7 +142,8 @@ public class TabListSceneLayer extends SceneLayer {
             LayerTitleCache layerTitleCache, TabContentManager tabContentManager,
             ResourceManager resourceManager);
     private native void nativePutTabLayer(long nativeTabListSceneLayer, int id,
-            int toolbarResourceId, int closeButtonResourceId, int shadowResourceId,
+            int toolbarResourceId, int toolbarShadowResourceId,
+            int closeButtonResourceId, int shadowResourceId,
             int contourResourceId, int backLogoResourceId, int borderResourceId,
             int borderInnerShadowResourceId, boolean canUseLiveLayer, int tabBackgroundColor,
             int backLogoColor, boolean incognito, boolean isPortrait, float x, float y, float width,
@@ -149,5 +156,6 @@ public class TabListSceneLayer extends SceneLayer {
             int toolbarBackgroundColor, int closeButtonColor, boolean anonymizeToolbar,
             int toolbarTextBoxResource, int toolbarTextBoxBackgroundColor,
             float toolbarTextBoxAlpha, float toolbarAlpha, float toolbarYOffset,
-            float sideBorderScale, boolean attachContent, boolean insetVerticalBorder);
+            float sideBorderScale, boolean attachContent, boolean insetVerticalBorder,
+            boolean needsToolbarShadow);
 }