Use the pinch viewport offset for tap disambiguation.

Obtain the inner viewport origin, touch and target rectangles
from the Blink relative to the outer viewport.
Use the zoom rectangle in the outer viewport coordinates for bitmap
generation but the inner viewport coordinates for the calculation
of the physical window zoom rect.

This change is part 2 of 2 (part 1 is Blink side change https://codereview.chromium.org/584893004).

BUG=370470

Review URL: https://codereview.chromium.org/595693002

Cr-Commit-Position: refs/heads/master@{#296786}

content/renderer/render_view_impl.cc

@@ -4012,7 +4012,8 @@ void RenderViewImpl::OnEnableViewSourceMode() {
 
 #if defined(OS_ANDROID) || defined(TOOLKIT_VIEWS)
 bool RenderViewImpl::didTapMultipleTargets(
-    const blink::WebGestureEvent& event,
+    const WebSize& inner_viewport_offset,
+    const WebRect& touch_rect,
     const WebVector<WebRect>& target_rects) {
   // Never show a disambiguation popup when accessibility is enabled,
   // as this interferes with "touch exploration".
@@ -4024,13 +4025,12 @@ bool RenderViewImpl::didTapMultipleTargets(
   if (matches_accessibility_mode_complete)
     return false;
 
-  gfx::Rect finger_rect(
-      event.x - event.data.tap.width / 2, event.y - event.data.tap.height / 2,
-      event.data.tap.width, event.data.tap.height);
+  // The touch_rect, target_rects and zoom_rect are in the outer viewport
+  // reference frame.
   gfx::Rect zoom_rect;
   float new_total_scale =
       DisambiguationPopupHelper::ComputeZoomAreaAndScaleFactor(
-          finger_rect, target_rects, GetSize(),
+          touch_rect, target_rects, GetSize(),
           gfx::Rect(webview()->mainFrame()->visibleContentRect()).size(),
           device_scale_factor_ * webview()->pageScaleFactor(), &zoom_rect);
   if (!new_total_scale)
@@ -4070,8 +4070,13 @@ bool RenderViewImpl::didTapMultipleTargets(
         webwidget_->paintCompositedDeprecated(&canvas, zoom_rect);
       }
 
+      gfx::Rect zoom_rect_in_screen =
+          zoom_rect - gfx::Vector2d(inner_viewport_offset.width,
+                                    inner_viewport_offset.height);
+
       gfx::Rect physical_window_zoom_rect = gfx::ToEnclosingRect(
-          ClientRectToPhysicalWindowRect(gfx::RectF(zoom_rect)));
+          ClientRectToPhysicalWindowRect(gfx::RectF(zoom_rect_in_screen)));
+
       Send(new ViewHostMsg_ShowDisambiguationPopup(routing_id_,
                                                    physical_window_zoom_rect,
                                                    canvas_size,

content/renderer/render_view_impl.h

@@ -409,7 +409,8 @@ class CONTENT_EXPORT RenderViewImpl
   virtual void didUpdateLayout();
 #if defined(OS_ANDROID) || defined(TOOLKIT_VIEWS)
   virtual bool didTapMultipleTargets(
-      const blink::WebGestureEvent& event,
+      const blink::WebSize& inner_viewport_offset,
+      const blink::WebRect& touch_rect,
       const blink::WebVector<blink::WebRect>& target_rects);
 #endif
   virtual blink::WebString acceptLanguages();