Update SDK README to discuss about:tracing and observatory.

TBR=ianh@google.com

Review URL: https://codereview.chromium.org/1114553004

sky/sdk/README.md

diff --git a/sky/sdk/README.md b/sky/sdk/README.md
index 1531912..e27175d 100644
--- a/sky/sdk/README.md
+++ b/sky/sdk/README.md
@@ -133,12 +133,32 @@
 The `sky` pub package includes a `sky_tool` script to assist in running
 Sky applications inside the `SkyDemo.apk` harness.
 
-1. ``packages/sky/lib/sky_tool start --install examples/stocks/main.sky``
+1. ``packages/sky/sky_tool start --install examples/stocks/main.sky``
    The --install flag is only necessary to install SkyDemo.apk if not already
    installed from the Google Play store.
 
 2.  Use ``adb logcat`` to view any errors or Dart print() output from the app.
 
+Measuring Performance
+---------------------
+
+Sky has support for generating trace files compatible with
+[Chrome's about:tracing](https://www.chromium.org/developers/how-tos/trace-event-profiling-tool).
+
+`packages/sky/sky_tool start_tracing` and `packages/sky/sky_tool stop_tracing`
+are the commands to use.
+
+Due to https://github.com/domokit/mojo/issues/127 tracing currently
+requires root access on the device.
+
+Debugging
+---------
+
+Dart's [Observatory](https://www.dartlang.org/tools/observatory/)
+(VM Debugger & Profiler) support in Sky is
+[in progress](https://codereview.chromium.org/1107803002) and should
+be released shortly after Dart Summit 2015.
+
 Building a standalone MyApp
 ---------------------------
 

sky/sdk/packages/sky/CHANGELOG.md

diff --git a/sky/sdk/packages/sky/CHANGELOG.md b/sky/sdk/packages/sky/CHANGELOG.md
index b0eea7b..a92fef1 100644
--- a/sky/sdk/packages/sky/CHANGELOG.md
+++ b/sky/sdk/packages/sky/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.0.5+dart-summit-7
+
+  - Fix crash in sky_tool stop_tracing.
+
 ## 0.0.5+dart-summit-6
 
   - Fix missing include in sky_tool causing failure.

sky/sdk/packages/sky/lib/sky_tool

diff --git a/sky/sdk/packages/sky/lib/sky_tool b/sky/sdk/packages/sky/lib/sky_tool
index 59264ab..1dfe317 100755
--- a/sky/sdk/packages/sky/lib/sky_tool
+++ b/sky/sdk/packages/sky/lib/sky_tool
@@ -13,6 +13,7 @@
 import subprocess
 import sys
 import urlparse
+import time
 
 # TODO(eseidel): This should be BIN_DIR.
 LIB_DIR = os.path.realpath(os.path.dirname(os.path.abspath(__file__)))