[telemetry] Add support for requesting memory dumps via extension API

tools/telemetry/telemetry/internal/browser/tab.py

Index: tools/telemetry/telemetry/internal/browser/tab.py
diff --git a/tools/telemetry/telemetry/internal/browser/tab.py b/tools/telemetry/telemetry/internal/browser/tab.py
index 9c1f79f9e16471b44df3ff6fc4036d0fd04435c2..f78c2297f4e92a9ab280b583dd89f24cb04abaa2 100644
--- a/tools/telemetry/telemetry/internal/browser/tab.py
+++ b/tools/telemetry/telemetry/internal/browser/tab.py
@@ -257,3 +257,26 @@ class Tab(web_contents.WebContents):
     """)
     if force:
       self.Navigate('about:blank')
+
+  def DumpMemory(self, timeout=DEFAULT_TAB_TIMEOUT):
+    """Dumps memory.
+
+    Returns:
+      GUID of the generated dump if successful, None otherwise.
+
+    Raises:
+      exceptions.EvaluateException
+      exceptions.WebSocketDisconnected
+      exceptions.TimeoutException
+      exceptions.DevtoolsTargetCrashException
+    """
+    self.ExecuteJavaScript("""
+      window.__telemetry_memory_dump_guid = undefined;
+      chrome.memoryBenchmarking.requestMemoryDump(function(dumpGuid, success) {
+        window.__telemetry_memory_dump_guid = success ? dumpGuid : null;
+      });
+    """, timeout)
+    self.WaitForJavaScriptExpression(
+        'window.__telemetry_memory_dump_guid !== undefined', timeout)
+    return self.EvaluateJavaScript(
+        'window.__telemetry_memory_dump_guid', timeout)

[Primiano Tucci (use gerrit), 2015/07/24 14:33:29]

maybe you walso want to clear the global __telemetry...guid here?