Fix Magic Mouse history swiping bug.

Magic Mouse gestures don't cause -touches*WithEvent: events to be sent down the
responder chain. As such, all state related to Magic Mouse gestures needs to be
reset during -beginGestureWithEvent:.

BUG=317161

Review URL: https://codereview.chromium.org/821173003

Cr-Commit-Position: refs/heads/master@{#311762}

chrome/browser/renderer_host/chrome_render_widget_host_view_mac_history_swiper.h

@@ -113,6 +113,18 @@ enum RecognitionState {
 //   that it can decide whether to consume the events and prevent them from
 //   being passed to the renderer. This API is used to transition from kPending
 //   -> kPotential.
+//
+//  This class is also responsible for handling gestures from a Magic Mouse.
+//  Magic Mouse gestures do not generate -touches*WithEvent: callbacks, so this
+//  class must use the API -[NSEvent trackSwipeEventWithOptions:...] to track
+//  the Magic Mouse gesture. Due to an AppKit bug, once this API is invoked,
+//  views no longer reliable receive -touches*WithEvent: callbacks. As such,
+//  once this class invokes the -[NSEvent trackSwipeEventWithOptions:...] API,
+//  it must continue to use that API, since it no longer receives touch events.
+//
+//  TODO(erikchen): Even for users that do not have a Magic Mouse, this class
+//  will sometime transition into Magic Mouse mode. This is very undesirable.
+//  See http://crbug.com/317161 for more details.
 @class HistoryOverlayController;
 @interface HistorySwiper : NSObject {
  @private
@@ -149,7 +161,7 @@ enum RecognitionState {
   id<HistorySwiperDelegate> delegate_;
 
   // Cumulative scroll delta since scroll gesture start. Only valid during
-  // scroll gesture handling. Used for history swiping.
+  // scroll gesture handling. Only used to trigger Magic Mouse history swiping.
   NSSize mouseScrollDelta_;
 }
 
@@ -162,10 +174,14 @@ enum RecognitionState {
 
 // The event passed in is a gesture event, and has touch data associated with
 // the trackpad.
+// Once the method -[NSEvent trackSwipeEventWithOptions:...] is invoked, the
+// methods -touches*WithEvent: are no longer guaranteed to be called for
+// subsequent gestures. http://crbug.com/317161
 - (void)touchesBeganWithEvent:(NSEvent*)event;
 - (void)touchesMovedWithEvent:(NSEvent*)event;
 - (void)touchesCancelledWithEvent:(NSEvent*)event;
 - (void)touchesEndedWithEvent:(NSEvent*)event;
+
 - (void)beginGestureWithEvent:(NSEvent*)event;
 - (void)endGestureWithEvent:(NSEvent*)event;
 

chrome/browser/renderer_host/chrome_render_widget_host_view_mac_history_swiper.mm

@@ -163,6 +163,9 @@ BOOL forceMagicMouse = NO;
 
 - (void)beginGestureWithEvent:(NSEvent*)event {
   inGesture_ = YES;
+
+  // Reset state pertaining to Magic Mouse swipe gestures.
+  mouseScrollDelta_ = NSZeroSize;
 }
 
 - (void)endGestureWithEvent:(NSEvent*)event {
@@ -213,10 +216,9 @@ BOOL forceMagicMouse = NO;
 - (void)touchesBeganWithEvent:(NSEvent*)event {
   receivingTouches_ = YES;
 
-  // Reset state pertaining to previous gestures.
+  // Reset state pertaining to previous trackpad gestures.
   gestureStartPointValid_ = NO;
   gestureTotalY_ = 0;
-  mouseScrollDelta_ = NSZeroSize;
   beganEventUnconsumed_ = NO;
   recognitionState_ = history_swiper::kPending;
 }

chrome/browser/renderer_host/chrome_render_widget_host_view_mac_history_swiper_unit_test.mm

@@ -90,6 +90,7 @@ class MacHistorySwiperTest : public CocoaTest {
     CocoaTest::TearDown();
   }
 
+  // These methods send all 3 types of events: gesture, scroll, and touch.
   void startGestureInMiddle();
   void moveGestureInMiddle();
   void moveGestureAtPoint(NSPoint point);
@@ -97,6 +98,10 @@ class MacHistorySwiperTest : public CocoaTest {
   void endGestureAtPoint(NSPoint point);
   void rendererACKForBeganEvent();
 
+  // These methods send a single type of event.
+  void sendBeginGestureEventInMiddle();
+  void sendEndGestureEventAtPoint(NSPoint point);
+
   HistorySwiper* historySwiper_;
   NSView* view_;
   int begin_count_;
@@ -189,6 +194,8 @@ void MacHistorySwiperTest::endGestureAtPoint(NSPoint point) {
 
   NSEvent* scrollEvent = scrollWheelEventWithPhase(NSEventPhaseEnded);
   [historySwiper_ handleEvent:scrollEvent];
+
+  sendEndGestureEventAtPoint(point);
 }
 
 void MacHistorySwiperTest::rendererACKForBeganEvent() {
@@ -197,6 +204,16 @@ void MacHistorySwiperTest::rendererACKForBeganEvent() {
   [historySwiper_ rendererHandledWheelEvent:event consumed:NO];
 }
 
+void MacHistorySwiperTest::sendBeginGestureEventInMiddle() {
+  NSEvent* event = mockEventWithPoint(makePoint(0.5, 0.5), NSEventTypeGesture);
+  [historySwiper_ beginGestureWithEvent:event];
+}
+
+void MacHistorySwiperTest::sendEndGestureEventAtPoint(NSPoint point) {
+  NSEvent* event = mockEventWithPoint(point, NSEventTypeGesture);
+  [historySwiper_ endGestureWithEvent:event];
+}
+
 // Test that a simple left-swipe causes navigation.
 TEST_F(MacHistorySwiperTest, SwipeLeft) {
   // These tests require 10.7+ APIs.
@@ -472,3 +489,59 @@ TEST_F(MacHistorySwiperTest, SubstantialVerticalThenHorizontal) {
   EXPECT_FALSE(navigated_right_);
   EXPECT_FALSE(navigated_left_);
 }
+
+// Magic Mouse gestures don't send -touches*WithEvent: callbacks. The history
+// swiper should still handle this gracefully. It should not turn vertical
+// motion into history swipes.
+TEST_F(MacHistorySwiperTest, MagicMouseStateResetsCorrectly) {
+  // These tests require 10.7+ APIs.
+  if (![NSEvent
+          respondsToSelector:@selector(isSwipeTrackingFromScrollEventsEnabled)])
+    return;
+
+  // Magic mouse events don't generate '-touches*WithEvent:' callbacks.
+  // Send the following events:
+  //  - beginGesture
+  //  - scrollWheel: (phase=Began)
+  //  - scrollWheel: (phase=Changed), significant horizontal motion.
+  //  - scrollWheel: (phase=Ended)
+  //  - endGesture
+  sendBeginGestureEventInMiddle();
+  [historySwiper_ handleEvent:scrollWheelEventWithPhase(NSEventPhaseBegan)];
+
+  // Callback from Blink to set the relevant state for history swiping.
+  rendererACKForBeganEvent();
+
+  NSEvent* scrollEvent = scrollWheelEventWithPhase(NSEventPhaseChanged,
+                                                   NSEventPhaseNone, 200.0, 0);
+  [historySwiper_ handleEvent:scrollEvent];
+  [historySwiper_ handleEvent:scrollWheelEventWithPhase(NSEventPhaseEnded)];
+  sendEndGestureEventAtPoint(makePoint(0.7, 0.5));
+
+  // Expect this sequence of events to trigger a magic mouse history swipe.
+  EXPECT_TRUE(magic_mouse_history_swipe_);
+
+  // Reset state.
+  magic_mouse_history_swipe_ = false;
+
+  // Send the following events:
+  //  - beginGesture
+  //  - scrollWheel: (phase=Began)
+  //  - scrollWheel: (phase=Changed), significant vertical motion.
+  //  - scrollWheel: (phase=Ended)
+  //  - endGesture
+  sendBeginGestureEventInMiddle();
+  [historySwiper_ handleEvent:scrollWheelEventWithPhase(NSEventPhaseBegan)];
+
+  // Callback from Blink to set the relevant state for history swiping.
+  rendererACKForBeganEvent();
+
+  scrollEvent =
+      scrollWheelEventWithPhase(NSEventPhaseChanged, NSEventPhaseNone, 0, 20);
+  [historySwiper_ handleEvent:scrollEvent];
+  [historySwiper_ handleEvent:scrollWheelEventWithPhase(NSEventPhaseEnded)];
+  sendEndGestureEventAtPoint(makePoint(0.5, 0.7));
+
+  // Vertical motion should never trigger a history swipe!
+  EXPECT_FALSE(magic_mouse_history_swipe_);
+}