Adds DevTools commands for forced viewport override.

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 326712afcbc2f0488f9b643f30838e9d9ef96685..18f0968bfc7c2d6d62edf9a7ff85eec987f224ba 100644
--- a/third_party/WebKit/Source/web/InspectorEmulationAgent.cpp
+++ b/third_party/WebKit/Source/web/InspectorEmulationAgent.cpp
@@ -10,6 +10,7 @@
 #include "core/page/Page.h"
 #include "platform/geometry/DoubleRect.h"
 #include "public/platform/Platform.h"
+#include "public/platform/WebFloatPoint.h"
 #include "public/platform/WebThread.h"
 #include "public/platform/WebViewScheduler.h"
 #include "web/DevToolsEmulator.h"
@@ -61,6 +62,29 @@ void InspectorEmulationAgent::disable(ErrorString*)
     setScriptExecutionDisabled(&error, false);
     setTouchEmulationEnabled(&error, false, protocol::Maybe<String>());
     setEmulatedMedia(&error, String());
+    resetViewport(&error);
+}
+
+void InspectorEmulationAgent::forceViewport(ErrorString* error, double x, double y, const Maybe<double>& scale)
+{
+    if (x < 0 || y < 0) {
+        *error = "Coordinates must be non-negative";
+        return;
+    }
+
+    float appliedScale = scale.fromMaybe(1.f);
+    if (appliedScale <= 0) {
+        *error = "Scale must be positive";
+        return;
+    }
+
+    WebFloatPoint position(x, y);
+    webViewImpl()->devToolsEmulator()->forceViewport(position, appliedScale);

[dgozman, 2016/08/29 20:45:36]

We should store the values in |m_state| and restore from them in |restore()|.
This ensures we preserve the values upon cross-process navigation.

[Eric Seckler, 2016/09/12 13:58:00]

Done.

+}
+
+void InspectorEmulationAgent::resetViewport(ErrorString*)
+{
+    webViewImpl()->devToolsEmulator()->resetViewport();
 }
 
 void InspectorEmulationAgent::resetPageScaleFactor(ErrorString*)