Make sudden termination into a counter.

We were incorrectly interpreting enableSuddenTermination to mean "enable sudden termination". Really it should just decrement a counter, and we should only enable sudden termination when that counter reaches 0.

Related to, but not the fix for, http://crbug.com/5638

This may have been causing memory corruption due to shutting down the renderer process while writing to a storage area or icon database (although honestly I don't actually know if we even use those parts of webkit).

Also, add a ui test that fails before this patch and succeeds with this patch.

BUG=none
TEST=sudden termination still works on a simple page

Review URL: http://codereview.chromium.org/245036

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@27831 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 21 insertions, 0 deletions

diff --git a/chrome/renderer/renderer_webkitclient_impl.cc b/chrome/renderer/renderer_webkitclient_impl.cc
index 3907b53..2a2ae60 100644
--- a/chrome/renderer/renderer_webkitclient_impl.cc
+++ b/chrome/renderer/renderer_webkitclient_impl.cc
@@ -132,6 +132,19 @@ WebString RendererWebKitClientImpl::defaultLocale() {
 }
 
 void RendererWebKitClientImpl::suddenTerminationChanged(bool enabled) {
+  if (enabled) {
+    // We should not get more enables than disables, but we want it to be a
+    // non-fatal error if it does happen.
+    DCHECK_GT(sudden_termination_disables_, 0);
+    sudden_termination_disables_ = std::max(--sudden_termination_disables_, 0);
+    if (sudden_termination_disables_ != 0)
+      return;
+  } else {
+    sudden_termination_disables_++;
+    if (sudden_termination_disables_ != 1)
+      return;
+  }
+
   RenderThread* thread = RenderThread::current();
   if (thread)  // NULL in unittests.
     thread->Send(new ViewHostMsg_SuddenTerminationChanged(enabled));
diff --git a/chrome/renderer/renderer_webkitclient_impl.h b/chrome/renderer/renderer_webkitclient_impl.h
index d610458..f85ba2f 100644
--- a/chrome/renderer/renderer_webkitclient_impl.h
+++ b/chrome/renderer/renderer_webkitclient_impl.h
@@ -21,6 +21,8 @@
 
 class RendererWebKitClientImpl : public webkit_glue::WebKitClientImpl {
  public:
+  RendererWebKitClientImpl() : sudden_termination_disables_(0) {}
+
   // WebKitClient methods:
   virtual WebKit::WebClipboard* clipboard();
   virtual WebKit::WebMimeRegistry* mimeRegistry();
@@ -89,6 +91,12 @@ class RendererWebKitClientImpl : public webkit_glue::WebKitClientImpl {
 #if defined(OS_WIN) || defined(OS_LINUX)
   SandboxSupport sandbox_support_;
 #endif
+
+  // This counter keeps track of the number of times sudden termination is
+  // enabled or disabled. It starts at 0 (enabled) and for every disable
+  // increments by 1, for every enable decrements by 1. When it reaches 0,
+  // we tell the browser to enable fast termination.
+  int sudden_termination_disables_;
 };
 
 #endif  // CHROME_RENDERER_WEBKIT_CLIENT_IMPL_H_