Migrate Telemetry from beginWindowSnapshotPNG to Page.captureScreenshot

tools/telemetry/telemetry/core/backends/chrome/inspector_backend.py

Index: tools/telemetry/telemetry/core/backends/chrome/inspector_backend.py
diff --git a/tools/telemetry/telemetry/core/backends/chrome/inspector_backend.py b/tools/telemetry/telemetry/core/backends/chrome/inspector_backend.py
index bd7680c073da3163389ecb311ae6b015ebe2c0e8..07acc758bb9c9cbf87a876331bb9e67e4a544f6c 100644
--- a/tools/telemetry/telemetry/core/backends/chrome/inspector_backend.py
+++ b/tools/telemetry/telemetry/core/backends/chrome/inspector_backend.py
@@ -96,44 +96,14 @@ class InspectorBackend(inspector_websocket.InspectorWebsocket):
       # Displays other than 0 mean we are likely running in something like
       # xvfb where screenshotting doesn't work.
       return False
-    return not self.EvaluateJavaScript("""
-        window.chrome.gpuBenchmarking === undefined ||
-        window.chrome.gpuBenchmarking.beginWindowSnapshotPNG === undefined
-      """)
+    return True
 
   def Screenshot(self, timeout):
     assert self.screenshot_supported, 'Browser does not support screenshotting'
 
-    self.EvaluateJavaScript("""
-        if(!window.__telemetry) {
-          window.__telemetry = {}
-        }
-        window.__telemetry.snapshotComplete = false;
-        window.__telemetry.snapshotData = null;
-        window.chrome.gpuBenchmarking.beginWindowSnapshotPNG(
-          function(snapshot) {
-            window.__telemetry.snapshotData = snapshot;
-            window.__telemetry.snapshotComplete = true;
-          }
-        );
-    """)
-
-    def IsSnapshotComplete():
-      return self.EvaluateJavaScript(
-          'window.__telemetry.snapshotComplete')
-
-    util.WaitFor(IsSnapshotComplete, timeout)
-
-    snap = self.EvaluateJavaScript("""
-      (function() {
-        var data = window.__telemetry.snapshotData;
-        delete window.__telemetry.snapshotComplete;
-        delete window.__telemetry.snapshotData;
-        return data;
-      })()
-    """)
-    if snap:
-      return bitmap.Bitmap.FromBase64Png(snap['data'])
+    response = self.SyncRequest({'method': 'Page.captureScreenshot'}, timeout)
+    if response:
+      return bitmap.Bitmap.FromBase64Png(response['result']['data'])
     return None
 
   # Console public methods.