input: Restrict synthetic touch gesture to view bounds.

content/browser/renderer_host/input/synthetic_touchscreen_pinch_gesture.cc

Index: content/browser/renderer_host/input/synthetic_touchscreen_pinch_gesture.cc
diff --git a/content/browser/renderer_host/input/synthetic_touchscreen_pinch_gesture.cc b/content/browser/renderer_host/input/synthetic_touchscreen_pinch_gesture.cc
index 8daff81a14c7d69fc08b60b5b4263a15425c335d..118003f1dcb7cb25ae4c2b9291b446ec1e95e4db 100644
--- a/content/browser/renderer_host/input/synthetic_touchscreen_pinch_gesture.cc
+++ b/content/browser/renderer_host/input/synthetic_touchscreen_pinch_gesture.cc
@@ -6,6 +6,7 @@
 
 #include <stdint.h>
 
+#include <algorithm>
 #include <cmath>
 
 #include "base/logging.h"
@@ -96,9 +97,11 @@ void SyntheticTouchscreenPinchGesture::MoveTouchPoints(
     SyntheticGestureTarget* target,
     float delta,
     const base::TimeTicks& timestamp) {
+  gfx::Size view_size = target->GetViewSize();
   // The two pointers move in opposite directions.
-  float current_y_0 = start_y_0_ + delta;
-  float current_y_1 = start_y_1_ - delta;
+  float current_y_0 = std::max(start_y_0_ + delta, 0.f);
+  float current_y_1 =
+      std::min(start_y_1_ - delta, static_cast<float>(view_size.height() - 1));
 
   synthetic_pointer_driver_->Move(params_.anchor.x(), current_y_0, 0);
   synthetic_pointer_driver_->Move(params_.anchor.x(), current_y_1, 1);
@@ -132,8 +135,10 @@ void SyntheticTouchscreenPinchGesture::SetupCoordinatesAndStopTime(
         target->GetTouchSlopInDips();
   }
 
-  start_y_0_ = params_.anchor.y() - initial_distance_to_anchor;
-  start_y_1_ = params_.anchor.y() + initial_distance_to_anchor;
+  gfx::Size view_size = target->GetViewSize();
+  start_y_0_ = std::max(params_.anchor.y() - initial_distance_to_anchor, 0.f);
+  start_y_1_ = std::min(params_.anchor.y() + initial_distance_to_anchor,
+                        static_cast<float>(view_size.height() - 1));
 
   max_pointer_delta_0_ = initial_distance_to_anchor - final_distance_to_anchor;