Increase heap limit for DevTools isolate.

third_party/WebKit/Source/web/WebDevToolsFrontendImpl.cpp

Index: third_party/WebKit/Source/web/WebDevToolsFrontendImpl.cpp
diff --git a/third_party/WebKit/Source/web/WebDevToolsFrontendImpl.cpp b/third_party/WebKit/Source/web/WebDevToolsFrontendImpl.cpp
index 637f5d8cd273ef2c0efcffa263ac2d9ab098d3e6..3409a5ba6aba43d45225480d970c1092a5caa066 100644
--- a/third_party/WebKit/Source/web/WebDevToolsFrontendImpl.cpp
+++ b/third_party/WebKit/Source/web/WebDevToolsFrontendImpl.cpp
@@ -65,6 +65,9 @@ WebDevToolsFrontendImpl::~WebDevToolsFrontendImpl() {
 void WebDevToolsFrontendImpl::didClearWindowObject(WebLocalFrameImpl* frame) {
   if (m_webFrame == frame) {
     v8::Isolate* isolate = v8::Isolate::GetCurrent();
+    // Use higher limit for DevTools isolate so that it does not OOM when
+    // taking large heap snapshots.
+    isolate->IncreaseHeapLimitForDebugging();

[alph, 2017/01/12 17:03:22]

I wonder why it helps. Most of the heap snapshot data (nodes and edges) are
stored in external arrays. The only thing which is within the heap is strings.
However they shouldn't occupy more space than they do in the inspected heap.
Moreover, each snapshot is stored in a dedicated worker heap, so increasing main
isolate heap should have no effect.

Do you have an example page that OOMs? I'm curious to take a look.. 

     ScriptState* scriptState = ScriptState::forMainWorld(m_webFrame->frame());
     DCHECK(scriptState);
     ScriptState::Scope scope(scriptState);