Allow the bottom sheet to be dragged down from the toolbar

This patch adds an explicit function to the SwipeableBottomSheet that
determines if a touch event is inside of the sheet's toolbar. This
eliminates the hack that existed previously that made too many
assumptions about the height of the toolbar.

Bug: 834795
Change-Id: Id195e72718ff2d37deb2891fd6264300d517352a
Reviewed-on: https://chromium-review.googlesource.com/1036224
Commit-Queue: Matthew Jones <mdjones@chromium.org>
Reviewed-by: Theresa <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#555873}

chrome/android/java/res/layout/bottom_sheet.xml

@@ -41,7 +41,7 @@
             <View
                 android:id="@+id/bottom_sheet_toolbar"
                 android:layout_width="match_parent"
-                android:layout_height="match_parent"
+                android:layout_height="@dimen/bottom_control_container_peek_height"
                 android:background="@color/modern_primary_color" />
         </view>
 

chrome/android/java/src/org/chromium/chrome/browser/widget/bottomsheet/BottomSheet.java

@@ -153,6 +153,9 @@ public class BottomSheet extends FrameLayout
     /** The visible rect for the screen taking the keyboard into account. */
     private final Rect mVisibleViewportRect = new Rect();
 
+    /** An out-array for use with getLocationInWindow to prevent constant allocations. */
+    private final int[] mCachedLocation = new int[2];
+
     /** The minimum distance between half and full states to allow the half state. */
     private final float mMinHalfFullDistance;
 
@@ -717,6 +720,15 @@ public class BottomSheet extends FrameLayout
         return (swipeToDismissEnabled() ? getHiddenRatio() : getPeekRatio()) * mContainerHeight;
     }
 
+    @Override
+    public boolean isTouchEventInToolbar(MotionEvent event) {
+        mToolbarHolder.getLocationInWindow(mCachedLocation);
+        // This check only tests for collision for the Y component since the sheet is the full width
+        // of the screen. We only care if the touch event is above the bottom of the toolbar since
+        // we won't receive an event if the touch is outside the sheet.
+        return mCachedLocation[1] + mToolbarHolder.getHeight() > event.getRawY();
+    }
+
     /**
      * @return Whether flinging down hard enough will close the sheet.
      */
@@ -737,11 +749,6 @@ public class BottomSheet extends FrameLayout
         return getFullRatio() * mContainerHeight;
     }
 
-    @Override
-    public float getContainerHeightPx() {
-        return mContainerHeight;
-    }
-
     /**
      * Show content in the bottom sheet's content area.
      * @param content The {@link BottomSheetContent} to show, or null if no content should be shown.

chrome/android/java/src/org/chromium/chrome/browser/widget/bottomsheet/BottomSheetSwipeDetector.java

@@ -71,10 +71,10 @@ public class BottomSheetSwipeDetector extends GestureDetector.SimpleOnGestureLis
         float getMaxOffsetPx();
 
         /**
-         * Gets the height of the container that the sheet exists in.
-         * @return The height of the sheet's container.
+         * @param event The motion event to test.
+         * @return Whether the provided motion event is inside the toolbar.
          */
-        float getContainerHeightPx();
+        boolean isTouchEventInToolbar(MotionEvent event);
 
         /**
          * Check if a particular gesture or touch event should move the bottom sheet when in peeking
@@ -123,7 +123,7 @@ public class BottomSheetSwipeDetector extends GestureDetector.SimpleOnGestureLis
                     mSheetDelegate.getCurrentOffsetPx(), mSheetDelegate.getMaxOffsetPx());
 
             // Allow the bottom sheet's content to be scrolled up without dragging the sheet down.
-            if (!isTouchEventInToolbar(e2) && isSheetInMaxPosition
+            if (!mSheetDelegate.isTouchEventInToolbar(e2) && isSheetInMaxPosition
                     && !mSheetDelegate.isContentScrolledToTop()) {
                 return false;
             }
@@ -253,17 +253,6 @@ public class BottomSheetSwipeDetector extends GestureDetector.SimpleOnGestureLis
         return rawEvent;
     }
 
-    /**
-     * Determines if a touch event is inside the toolbar. This assumes the toolbar is the full
-     * width of the screen and that the toolbar is at the top of the bottom sheet.
-     * @param e The motion event to test.
-     * @return True if the event occurred in the toolbar region.
-     */
-    private boolean isTouchEventInToolbar(MotionEvent e) {
-        return mSheetDelegate.getContainerHeightPx() - e.getRawY()
-                > mSheetDelegate.getCurrentOffsetPx() - mSheetDelegate.getMinOffsetPx();
-    }
-
     /**
      * Gets the distance of a fling based on the velocity and the base animation time. This formula
      * assumes the deceleration curve is quadratic (t^2), hence the displacement formula should be:

chrome/android/junit/src/org/chromium/chrome/browser/widget/bottomsheet/BottomSheetSwipeDetectorTest.java

@@ -91,8 +91,10 @@ public final class BottomSheetSwipeDetectorTest {
         }
 
         @Override
-        public float getContainerHeightPx() {
-            return mMaxOffset;
+        public boolean isTouchEventInToolbar(MotionEvent event) {
+            // This will be implementation specific in practice. This checks that the motion event
+            // occured above the bottom of the toolbar.
+            return event.getRawY() < (mMaxOffset - mCurrentSheetOffset) + mMinOffset;
         }
 
         @Override