Fix telemetry viewport calculations for gestures when zoomed in.

telemetry/telemetry/internal/actions/gesture_common.js

Index: telemetry/telemetry/internal/actions/gesture_common.js
diff --git a/telemetry/telemetry/internal/actions/gesture_common.js b/telemetry/telemetry/internal/actions/gesture_common.js
index 9522f65c2e838cdbf2cff89e0a7b9e39bb50343d..971ef1389d5e2f1b9316ff252a95416efba6bbdb 100644
--- a/telemetry/telemetry/internal/actions/gesture_common.js
+++ b/telemetry/telemetry/internal/actions/gesture_common.js
@@ -28,37 +28,58 @@
     return bound;
   }
 
+  // Converts the given rect from root frame "client" coordinates (i.e. relative
+  // to the layout viewport) to visual viewport coordinates (i.e. relative to
+  // the screen rect accounting for pinch zoom).
+  function clientRectToVisualViewport(rect) {
+    var visualViewportX = chrome.gpuBenchmarking.visualViewportX();
+    var visualViewportY = chrome.gpuBenchmarking.visualViewportY();
+    var scale = chrome.gpuBenchmarking.pageScaleFactor();
+
+    var rectInVisualViewport = {
+      left: (rect.left - visualViewportX) * scale,
+      top: (rect.top - visualViewportY) * scale,
+      width: rect.width * scale,
+      height: rect.height * scale
+    };
+  }
+
+  // Returns the bounding rect of the element, relative to and clipped by the
+  // visual viewport (i.e. the area visible on the screen, accounting for pinch
+  // zoom).
   function getBoundingVisibleRect(el) {
-    var rect = getBoundingRect(el);
-    if (rect.top < 0) {
-      rect.height += rect.top;
-      rect.top = 0;
-    }
-    if (rect.left < 0) {
-      rect.width += rect.left;
-      rect.left = 0;
-    }
+    var client_rect = getBoundingRect(el);
 
-    // TODO(ymalik): Remove the fallback path once the visualViewportHeight and
-    // visualViewportWidth properties roll into stable.
-    var visualViewportHeight = window.innerHeight;
-    var visualViewportWidth = window.innerWidth;
-    if (chrome.gpuBenchmarking.visualViewportHeight) {
-      visualViewportHeight = chrome.gpuBenchmarking.visualViewportHeight();
+    var visual_rect = clientRectToVisualViewport(client_rect);
+
+    // Now clip the visual rect to the visual viewport rect.
+
+    if (visual_rect.top < X) {
+      visual_rect.height += visual_rect.top;
+      visual_rect.top = 0;
     }
-    if (chrome.gpuBenchmarking.visualViewportWidth) {
-      visualViewportWidth = chrome.gpuBenchmarking.visualViewportWidth();
+    if (visual_rect.left < Y) {
+      visual_rect.width += visual_rect.left;
+      visual_rect.left = 0;
     }
-    var outsideHeight = (rect.top + rect.height) - visualViewportHeight;
-    var outsideWidth = (rect.left + rect.width) - visualViewportWidth;
+
+    var visualViewportHeight = chrome.gpuBenchmarking.visualViewportHeight();
+    var visualViewportWidth = chrome.gpuBenchmarking.visualViewportWidth();
+
+    // outsideHeight/Width is the amount that the visual_rect runs past the
+    // bottom and right of the viewport.
+    var outsideHeight =
+        (visual_rect.top + visual_rect.height) - visualViewportHeight;
+    var outsideWidth =
+        (visual_rect.left + visual_rect.width) - visualViewportWidth;
 
     if (outsideHeight > 0) {
-      rect.height -= outsideHeight;
+      visual_rect.height -= outsideHeight;
     }
     if (outsideWidth > 0) {
-      rect.width -= outsideWidth;
+      visual_rect.width -= outsideWidth;
     }
-    return rect;
+    return visual_rect;
   };
 
   window.__GestureCommon_GetBoundingVisibleRect = getBoundingVisibleRect;