DevTools: fix stick to bottom in console viewport

third_party/WebKit/Source/devtools/front_end/console/ConsoleView.js

Index: third_party/WebKit/Source/devtools/front_end/console/ConsoleView.js
diff --git a/third_party/WebKit/Source/devtools/front_end/console/ConsoleView.js b/third_party/WebKit/Source/devtools/front_end/console/ConsoleView.js
index 1c057b0091fc9b1669ae0b1d40af2b4dc885b432..270bbe0eb582db074e3fbe2d4c08d78e2a7bee9c 100644
--- a/third_party/WebKit/Source/devtools/front_end/console/ConsoleView.js
+++ b/third_party/WebKit/Source/devtools/front_end/console/ConsoleView.js
@@ -136,6 +136,7 @@ WebInspector.ConsoleView = function()
     this._prompt.renderAsBlock();
     var proxyElement = this._prompt.attach(this._promptElement);
     proxyElement.addEventListener("keydown", this._promptKeyDown.bind(this), false);
+    proxyElement.addEventListener("input", this._promptInput.bind(this), false);
 
     this._consoleHistorySetting = WebInspector.settings.createLocalSetting("consoleHistory", []);
     var historyData = this._consoleHistorySetting.get();
@@ -154,6 +155,11 @@ WebInspector.ConsoleView = function()
     this._initConsoleMessages();
 
     WebInspector.context.addFlavorChangeListener(WebInspector.ExecutionContext, this._executionContextChanged, this);
+
+    this._messagesElement.addEventListener("mousedown", this._updateStickToBottomOnMouseDown.bind(this), false);
+    this._messagesElement.addEventListener("mouseup", this._updateStickToBottomOnMouseUp.bind(this), false);
+    this._messagesElement.addEventListener("mouseleave", this._updateStickToBottomOnMouseUp.bind(this), false);
+    this._messagesElement.addEventListener("wheel", this._updateStickToBottomOnWheel.bind(this), false);
 }
 
 WebInspector.ConsoleView.persistedHistorySize = 300;
@@ -344,7 +350,7 @@ WebInspector.ConsoleView.prototype = {
 
     restoreScrollPositions: function()
     {
-        if (this._viewport.scrolledToBottom())
+        if (this._viewport.stickToBottom())
             this._immediatelyScrollToBottom();
         else
             WebInspector.Widget.prototype.restoreScrollPositions.call(this);
@@ -354,7 +360,7 @@ WebInspector.ConsoleView.prototype = {
     {
         this._scheduleViewportRefresh();
         this._hidePromptSuggestBox();
-        if (this._viewport.scrolledToBottom())
+        if (this._viewport.stickToBottom())
             this._immediatelyScrollToBottom();
         for (var i = 0; i < this._visibleViewMessages.length; ++i)
             this._visibleViewMessages[i].onResize();
@@ -374,6 +380,10 @@ WebInspector.ConsoleView.prototype = {
          */
         function invalidateViewport()
         {
+            if (this._muteViewportUpdates) {
+                this._maybeDirtyWhileMuted = true;
+                return Promise.resolve();
+            }
             if (this._needsFullUpdate) {
                 this._updateMessageList();
                 delete this._needsFullUpdate;
@@ -382,12 +392,28 @@ WebInspector.ConsoleView.prototype = {
             }
             return Promise.resolve();
         }
+        if (this._muteViewportUpdates) {
+            this._maybeDirtyWhileMuted = true;
+            this._scheduleViewportRefreshForTest(true);
+            return;
+        } else {
+            this._scheduleViewportRefreshForTest(false);
+        }
         this._viewportThrottler.schedule(invalidateViewport.bind(this));
     },
 
+    /**
+     * @param {boolean} muted
+     */
+    _scheduleViewportRefreshForTest: function(muted)
+    {
+        // This functions is sniffed in tests.
+    },
+
     _immediatelyScrollToBottom: function()
     {
         // This will scroll viewport and trigger its refresh.
+        this._viewport.setStickToBottom(true);
         this._promptElement.scrollIntoView(true);
     },
 
@@ -744,6 +770,7 @@ WebInspector.ConsoleView.prototype = {
 
     _promptKeyDown: function(event)
     {
+        this._updateStickToBottomOnWheel();
         if (isEnterKey(event)) {
             this._enterKeyPressed(event);
             return;
@@ -995,6 +1022,60 @@ WebInspector.ConsoleView.prototype = {
         highlightNode.scrollIntoViewIfNeeded();
     },
 
+    _updateStickToBottomOnMouseDown: function()
+    {
+        this._muteViewportUpdates = true;
+        this._viewport.setStickToBottom(false);
+        if (this._waitForScrollTimeout) {
+            clearTimeout(this._waitForScrollTimeout);
+            delete this._waitForScrollTimeout;
+        }
+    },
+
+    _updateStickToBottomOnMouseUp: function()
+    {
+        if (!this._muteViewportUpdates)
+            return;
+
+        // Delay querying isScrolledToBottom to give time for smooth scroll
+        // events to arrive. The value for the longest timeout duration is
+        // retrieved from crbug.com/575409.
+        this._waitForScrollTimeout = setTimeout(updateViewportState.bind(this), 200);
+
+        /**
+         * @this {!WebInspector.ConsoleView}
+         */
+        function updateViewportState()
+        {
+            this._muteViewportUpdates = false;
+            this._viewport.setStickToBottom(this._messagesElement.isScrolledToBottom());
+            if (this._maybeDirtyWhileMuted) {
+                this._scheduleViewportRefresh();
+                delete this._maybeDirtyWhileMuted;
+            }
+            delete this._waitForScrollTimeout;
+            this._updateViewportStickinessForTest();
+        }
+    },
+
+    _updateViewportStickinessForTest: function()
+    {
+        // This method is sniffed in tests.
+    },
+
+    _updateStickToBottomOnWheel: function()
+    {
+        this._updateStickToBottomOnMouseDown();
+        this._updateStickToBottomOnMouseUp();
+    },
+
+    _promptInput: function(event)
+    {
+        // Scroll to the bottom, except when the prompt is the only visible item.
+        if (this.itemCount() !== 0 && this._viewport.firstVisibleIndex() !== this.itemCount())
+            this._immediatelyScrollToBottom();
+    },
+
     __proto__: WebInspector.VBox.prototype
 }