Added Tab.SnapshotContent and MapsGL example to telemetry

tools/telemetry/telemetry/inspector_page.py

Index: tools/telemetry/telemetry/inspector_page.py
diff --git a/tools/telemetry/telemetry/inspector_page.py b/tools/telemetry/telemetry/inspector_page.py
index b37d33049e1a876e0834201b8260df3c1cbaa2be..64bf1e799a73721756b6a8f65124b3ab926d34b0 100644
--- a/tools/telemetry/telemetry/inspector_page.py
+++ b/tools/telemetry/telemetry/inspector_page.py
@@ -5,9 +5,13 @@ import json
 import logging
 
 from telemetry import util
+from telemetry import png_bitmap
+
+DEFAULT_SCREENSHOT_TIMEOUT = 60
 
 class InspectorPage(object):
-  def __init__(self, inspector_backend):
+  def __init__(self, inspector_backend, tab):
+    self._tab = tab
     self._inspector_backend = inspector_backend
     self._inspector_backend.RegisterDomain(
         'Page',
@@ -81,3 +85,34 @@ class InspectorPage(object):
       self._inspector_backend.SendAndIgnoreResponse(request)
 
     self.PerformActionAndWaitForNavigate(DoNavigate, timeout)
+
+  def Screenshot(self, timeout=DEFAULT_SCREENSHOT_TIMEOUT):
+    """Capture a screenshot of the window for rendering validation"""
+
+    if self._tab.runtime.Evaluate(
+        'window.chrome.gpuBenchmarking === undefined'):
+      raise Exception("Browser was not started with --enable-gpu-benchmarking")
+
+    if self._tab.runtime.Evaluate(
+        'window.chrome.gpuBenchmarking.windowSnapshot === undefined'):
+      raise Exception("Browser does not support window snapshot API.")
+
+    self._tab.runtime.Evaluate("""
+        window.chrome.gpuBenchmarking.snapshotComplete = false;
+        window.chrome.gpuBenchmarking.windowSnapshot(function(snapshot) {
+            window.chrome.gpuBenchmarking.snapshotData = snapshot;

[nduca, 2012/11/12 19:53:26]

would probably bebetter if you stash this outside the gpuBenchmarking object,
e.g. window.__telemetry.blahblahblah

+            window.chrome.gpuBenchmarking.snapshotComplete = true;
+        });
+    """)
+
+    def IsSnapshotComplete():
+      return self._tab.runtime.Evaluate(
+          'window.chrome.gpuBenchmarking.snapshotComplete')
+
+    util.WaitFor(IsSnapshotComplete, timeout)
+
+    snap = self._tab.runtime.Evaluate(
+        'window.chrome.gpuBenchmarking.snapshotData')
+    if snap:

[nduca, 2012/11/12 19:53:26]

should you delette the snapshotComplete and snapshotData after you retrieve it?

+      return png_bitmap.PngBitmap(snap['data'])
+    return None