CustomTabs: Add a way to send scrolling state of the bottom bar to client

- Adds a request setter for the callback. Set to false by default.
- Starts sending the callback from bottom bar delegate only when
completely hidden or shown.
- If the bottom bar is not set, use the toolbar values to send the same
signal, so that bottom bar can be set as desired

BUG=746648

Change-Id: I6f60dde5e39354b33503ce9553b67cf953a9b533
Reviewed-on: https://chromium-review.googlesource.com/578392
Commit-Queue: Yusuf Ozuysal <yusufo@chromium.org>
Reviewed-by: Benoit L <lizeb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#488289}

chrome/android/java/src/org/chromium/chrome/browser/customtabs/ClientManager.java

@@ -129,6 +129,7 @@ class ClientManager {
         private boolean mShouldHideDomain;
         private boolean mShouldPrerenderOnCellular;
         private boolean mShouldSendNavigationInfo;
+        private boolean mShouldSendBottomBarScrollState;
         private KeepAliveServiceConnection mKeepAliveConnection;
         private String mPredictedUrl;
         private long mLastMayLaunchUrlTimestamp;
@@ -414,6 +415,24 @@ class ClientManager {
         if (params != null) params.mShouldHideDomain = hide;
     }
 
+    /**
+     * @return Whether bottom bar scrolling state should be recorded and shared for the session.
+     */
+    public synchronized boolean shouldSendBottomBarScrollStateForSession(
+            CustomTabsSessionToken session) {
+        SessionParams params = mSessionParams.get(session);
+        return params != null ? params.mShouldSendBottomBarScrollState : false;
+    }
+
+    /**
+     * Sets whether bottom bar scrolling state should be recorded and shared for the session.
+     */
+    public synchronized void setSendBottomBarScrollingStateForSessionn(
+            CustomTabsSessionToken session, boolean send) {
+        SessionParams params = mSessionParams.get(session);
+        if (params != null) params.mShouldSendBottomBarScrollState = send;
+    }
+
     /**
      * @return Whether navigation info should be recorded and shared for the session.
      */

chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabBottomBarDelegate.java

@@ -211,6 +211,16 @@ class CustomTabBottomBarDelegate implements FullscreenListener {
     public void onControlsOffsetChanged(float topOffset, float bottomOffset,
             boolean needsAnimate) {
         if (mBottomBarView != null) mBottomBarView.setTranslationY(bottomOffset);
+        // If the bottom bar is not visible use the top controls as a guide to set state.
+        float offset = getBottomBarHeight() == 0 ? topOffset : bottomOffset;
+        float height = getBottomBarHeight() == 0 ? mFullscreenManager.getTopControlsHeight()
+                                                 : mFullscreenManager.getBottomControlsHeight();
+        // Avoid spamming this callback across process boundaries, by only sending messages at
+        // absolute transitions.
+        if (Math.abs(offset) == height || offset == 0) {
+            CustomTabsConnection.getInstance().onBottomBarScrollStateChanged(
+                    mDataProvider.getSession(), offset != 0);
+        }
     }
 
     @Override

chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java

@@ -80,6 +80,7 @@ public class CustomTabsConnection {
 
     @VisibleForTesting
     static final String PAGE_LOAD_METRICS_CALLBACK = "NavigationMetrics";
+    static final String BOTTOM_BAR_SCROLL_STATE_CALLBACK = "onBottomBarScrollStateChanged";
 
     // For CustomTabs.SpeculationStatusOnStart, see tools/metrics/enums.xml. Append only.
     private static final int SPECULATION_STATUS_ON_START_ALLOWED = 0;
@@ -777,6 +778,11 @@ public class CustomTabsConnection {
         return mClientManager.shouldSendNavigationInfoForSession(session);
     }
 
+    /** @see ClientManager#shouldSendBottomBarScrollStateForSession(CustomTabsSessionToken) */
+    public boolean shouldSendBottomBarScrollStateForSession(CustomTabsSessionToken session) {
+        return mClientManager.shouldSendBottomBarScrollStateForSession(session);
+    }
+
     /** See {@link ClientManager#getClientPackageNameForSession(CustomTabsSessionToken)} */
     public String getClientPackageNameForSession(CustomTabsSessionToken session) {
         return mClientManager.getClientPackageNameForSession(session);
@@ -845,6 +851,30 @@ public class CustomTabsConnection {
     public void sendNavigationInfo(
             CustomTabsSessionToken session, String url, String title, Bitmap screenshot) { }
 
+    /**
+     * Called when the bottom bar for the custom tab has been hidden or shown completely by user
+     * scroll.
+     *
+     * @param session The session that is linked with the custom tab.
+     * @param hidden Whether the bottom bar is hidden or shown.
+     */
+    public void onBottomBarScrollStateChanged(CustomTabsSessionToken session, boolean hidden) {
+        if (!shouldSendBottomBarScrollStateForSession(session)) return;
+        CustomTabsCallback callback = mClientManager.getCallbackForSession(session);
+
+        Bundle args = new Bundle();
+        args.putBoolean("hidden", hidden);
+        try {
+            callback.extraCallback(BOTTOM_BAR_SCROLL_STATE_CALLBACK, args);
+        } catch (Exception e) {
+            // Pokemon exception handling, see above and crbug.com/517023.
+            return;
+        }
+        if (mLogRequests) {
+            logCallback("extraCallback(" + BOTTOM_BAR_SCROLL_STATE_CALLBACK + ")", hidden);
+        }
+    }
+
     /**
      * Notifies the application of a navigation event.
      *