Test devtools screenshot capture with different scales

Bug: 1164610
Change-Id: I354b0a20e47d6890af3239437ac2315c7488de0b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2640917Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845305}

third_party/blink/web_tests/http/tests/inspector-protocol/page/page-captureScreenshot-clip-expected.txt

 Tests that screenshot works with clip
-{"x":0,"y":15018,"width":54,"height":54}
+{"format":"png","clip":{"x":0,"y":15018,"width":54,"height":54,"scale":1}}
 {
     id : <number>
     result : {
@@ -7,4 +7,20 @@ Tests that screenshot works with clip
     }
     sessionId : <string>
 }
+{"format":"png","clip":{"x":0,"y":15018,"width":54,"height":54,"scale":0.5}}
+{
+    id : <number>
+    result : {
+        data : iVBORw0KGgoAAAANSUhEUgAAABsAAAAbCAYAAACN1PRVAAAAAXNSR0IArs4c6QAAADdJREFUSInt1sEJADAIwMBYOrib26cTKBSSBe6bgCqWugBkzEtZnHmlExMTExMTExMT+xaLzSN+jecGM57D8TYAAAAASUVORK5CYII=
+    }
+    sessionId : <string>
+}
+{"format":"png","clip":{"x":0,"y":15018,"width":54,"height":54,"scale":2}}
+{
+    id : <number>
+    result : {
+        data : iVBORw0KGgoAAAANSUhEUgAAAGwAAABsCAYAAACPZlfNAAAAAXNSR0IArs4c6QAAASlJREFUeJzt1jEKAzEQBMGV8cPv53JsjOEuEg1VoaKBZkFrZu8h43V6AM8IFiNYzPvn5VoHZvDX9f3FcGExgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFiNYjGAxgsUIFrNm9j49gvtcWIxgMYLFfAD7MQbVV4On/QAAAABJRU5ErkJggg==
+    }
+    sessionId : <string>
+}
 

third_party/blink/web_tests/http/tests/inspector-protocol/page/page-captureScreenshot-clip.js

@@ -19,18 +19,24 @@
     <div class="above"></div>
     <div class="to-screenshot"></div>`, 'Tests that screenshot works with clip');
 
-  const json = await session.evaluate(`
+  const clip = await session.evaluate(`
     (() => {
       const div = document.querySelector('div.to-screenshot');
       const box = div.getBoundingClientRect();
       window.scrollTo(0, 15000);
-      return JSON.stringify({x: box.left, y: box.top, width: box.width, height: box.height});
+      return {x: box.left, y: box.top, width: box.width, height: box.height};
     })()
   `);
-  testRunner.log(json);
 
-  const clip = JSON.parse(json);
-  testRunner.log(await dp.Page.captureScreenshot({format: 'png', clip: {...clip, scale: 1}}));
+  async function test(scale) {
+    const params = {format: 'png', clip: {...clip, scale: scale}};
+    testRunner.log(JSON.stringify(params));
+    testRunner.log(await dp.Page.captureScreenshot(params));
+  }
+
+  await test(1);
+  await test(0.5);
+  await test(2);
 
   testRunner.completeTest();
 })
\ No newline at end of file