Emulation.setVirtualTimePolicy to have an optional virtual time budge

third_party/WebKit/Source/web/InspectorEmulationAgent.cpp

Index: third_party/WebKit/Source/web/InspectorEmulationAgent.cpp
diff --git a/third_party/WebKit/Source/web/InspectorEmulationAgent.cpp b/third_party/WebKit/Source/web/InspectorEmulationAgent.cpp
index 495b7921db61a413966621c2baca434874f0e78d..a004bd14433dfab4411f463678df5845fb7dc693 100644
--- a/third_party/WebKit/Source/web/InspectorEmulationAgent.cpp
+++ b/third_party/WebKit/Source/web/InspectorEmulationAgent.cpp
@@ -9,6 +9,8 @@
 #include "core/frame/Settings.h"
 #include "core/page/Page.h"
 #include "platform/geometry/DoubleRect.h"
+#include "public/platform/Platform.h"
+#include "public/platform/WebThread.h"
 #include "public/platform/WebViewScheduler.h"
 #include "web/DevToolsEmulator.h"
 #include "web/WebLocalFrameImpl.h"
@@ -29,6 +31,7 @@ InspectorEmulationAgent* InspectorEmulationAgent::create(WebLocalFrameImpl* webL
 
 InspectorEmulationAgent::InspectorEmulationAgent(WebLocalFrameImpl* webLocalFrameImpl, Client* client)
     : m_webLocalFrameImpl(webLocalFrameImpl)
+    , m_virtualTimeEnabled(false)
     , m_client(client)
 {
 }
@@ -93,18 +96,31 @@ void InspectorEmulationAgent::setCPUThrottlingRate(ErrorString*, double throttli
     m_client->setCPUThrottlingRate(throttlingRate);
 }
 
-void InspectorEmulationAgent::setVirtualTimePolicy(ErrorString*, const String& in_policy)
+void InspectorEmulationAgent::setVirtualTimePolicy(ErrorString*, const String& in_policy, const Maybe<double>& in_virtualTimeBudgetSeconds)
 {
     if (protocol::Emulation::VirtualTimePolicyEnum::Advance == in_policy) {
-        m_webLocalFrameImpl->view()->scheduler()->enableVirtualTime();
         m_webLocalFrameImpl->view()->scheduler()->setVirtualTimePolicy(WebViewScheduler::VirtualTimePolicy::ADVANCE);
     } else if (protocol::Emulation::VirtualTimePolicyEnum::Pause == in_policy) {
-        m_webLocalFrameImpl->view()->scheduler()->enableVirtualTime();
         m_webLocalFrameImpl->view()->scheduler()->setVirtualTimePolicy(WebViewScheduler::VirtualTimePolicy::PAUSE);
     } else if (protocol::Emulation::VirtualTimePolicyEnum::PauseIfNetworkFetchesPending == in_policy) {
-        m_webLocalFrameImpl->view()->scheduler()->enableVirtualTime();
         m_webLocalFrameImpl->view()->scheduler()->setVirtualTimePolicy(WebViewScheduler::VirtualTimePolicy::DETERMINISTIC_LOADING);
     }
+    if (!m_virtualTimeEnabled) {
+        m_webLocalFrameImpl->view()->scheduler()->enableVirtualTime();
+        m_virtualTimeEnabled = true;

[dgozman, 2016/08/01 16:03:31]

Should we instead make enableVirtualTime() idempotent and remove this flag?

[alex clarke (OOO till 29th), 2016/08/01 16:45:24]

Actually it is idempotent already. We can remove the flag :)

+    }
+
+    if (in_virtualTimeBudgetSeconds.isJust()) {

[dgozman, 2016/08/01 16:03:31]

What happens if client calls setVirtualTimePolicy twice, with different budgets
or policies? Let's maybe cancel previous timer?

[alex clarke (OOO till 29th), 2016/08/01 16:45:23]

Canceling the previous timer seems like the best approach.

+        WebTaskRunner* taskRunner = Platform::current()->currentThread()->getWebTaskRunner();
+        long long delayMillis = static_cast<long long>(in_virtualTimeBudgetSeconds.fromJust() * 1000.0);

[dgozman, 2016/08/01 16:03:31]

Let's make it milliseconds in protocol.

[alex clarke (OOO till 29th), 2016/08/01 16:45:24]

Done.

+        taskRunner->postDelayedTask(BLINK_FROM_HERE, WTF::bind(&InspectorEmulationAgent::virtualTimeBudgetExpired, wrapPersistent(this)), delayMillis);

[dgozman, 2016/08/01 16:03:31]

Can we use weak pointer here? If client detaches before this fires, we will have
a bunch of null pointer dereferences.

[alex clarke (OOO till 29th), 2016/08/01 16:45:23]

Good point.  Using CancellableTaskFactory here does that (it's based on
WeakPtr).

+    }
+}
+
+void InspectorEmulationAgent::virtualTimeBudgetExpired()
+{
+    m_webLocalFrameImpl->view()->scheduler()->setVirtualTimePolicy(WebViewScheduler::VirtualTimePolicy::PAUSE);
+    frontend()->virtualTimeBudgetExpired();
 }
 
 DEFINE_TRACE(InspectorEmulationAgent)