Introduce bottom controls to CC and let it respond to scrolling

content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java

Index: content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
index 7de8b4ae1d59448eb065e245f793592f7f3cf859..c5ce6ccb18e11c98dcb438228aa4c4f8e9392c33 100644
--- a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
+++ b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
@@ -501,6 +501,7 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Screen
     private int mPhysicalBackingWidthPix;
     private int mPhysicalBackingHeightPix;
     private int mTopControlsHeightPix;
+    private int mBottomControlsHeightPix;
     private boolean mTopControlsShrinkBlinkSize;
 
     // Cached copy of all positions and scales as reported by the renderer.
@@ -698,6 +699,15 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Screen
     }
 
     /**
+     * Sets the height of the bottom controls. If necessary, triggers a renderer resize.
+     */
+    public void setBottomControlsHeight(int bottomControlHeightPix) {
+        if (mBottomControlsHeightPix == bottomControlHeightPix) return;
+        mBottomControlsHeightPix = bottomControlHeightPix;
+        if (mNativeContentViewCore != 0) nativeWasResized(mNativeContentViewCore);
+    }
+
+    /**
      * Returns a delegate that can be used to add and remove views from the current
      * container view. Clients can safely hold to instances of this class as it handles the
      * replacement of container views transparently.
@@ -1096,6 +1106,11 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Screen
         return mTopControlsHeightPix;
     }
 
+    @CalledByNative
+    public int getBottomControlsHeightPix() {
+        return mBottomControlsHeightPix;
+    }
+
     /**
      * @return Current device scale factor (maps DIP pixels to physical pixels).
      */
@@ -2373,6 +2388,7 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Screen
             float contentWidth, float contentHeight,
             float viewportWidth, float viewportHeight,
             float controlsOffsetYCss, float contentOffsetYCss,
+            float bottomOffsetYCss, float bottomTranslateYCss,
             boolean isMobileOptimizedHint,
             boolean hasInsertionMarker, boolean isInsertionMarkerVisible,
             float insertionMarkerHorizontal, float insertionMarkerTop,
@@ -2440,6 +2456,9 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Screen
         getContentViewClient().onOffsetsForFullscreenChanged(
                 controlsOffsetPix, contentOffsetYPix);
 
+        getContentViewClient().onBottomOffsetChanged(bottomOffsetYCss * deviceScale,

[bokan, 2016/06/30 12:31:21]

Shouldn't we check if the offsets actually changed here?

[Ian Wen, 2016/07/01 02:51:44]

onOffsetsForFullscreenChanged() is the counterpart where we notifies the UI that
the top control has changed. Since it does not check if the values have actually
changed, I think to make it symmetric, we shouldn't check for the bottom as
well.

[bokan, 2016/07/01 17:19:13]

The documentation for that method also states that it's called when there's a
change. At the least, I would either change the names and comments on both these
methods to make it clear the values aren't necessarily changing or actually
check for changes before calling them. Anyway, this is well outside my domain,
Alexandre may have better guidance here.

[Ian Wen, 2016/07/06 20:53:44]

I changed the comments of the two methods so that they don't specifically
require the values to "change". Done.

+                bottomTranslateYCss * deviceScale);
+
         if (mBrowserAccessibilityManager != null) {
             mBrowserAccessibilityManager.notifyFrameInfoInitialized();
         }