DevTools(Protocol): expose BrowserContextId in TargetInfo

This patch exposes BrowserContextId as a part of TargetInfo.
This helps to attribute pages to the browser contexts they
belong to.

BUG=836272
R=dgozman

Change-Id: I93d54756c98124a077bd979c207c0c7cd7e38971
Reviewed-on: https://chromium-review.googlesource.com/1026391Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Commit-Queue: Andrey Lushnikov <lushnikov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553268}

content/browser/devtools/protocol/target_handler.cc

@@ -10,6 +10,7 @@
 #include "content/browser/devtools/devtools_manager.h"
 #include "content/browser/devtools/devtools_session.h"
 #include "content/browser/frame_host/navigation_handle_impl.h"
+#include "content/public/browser/browser_context.h"
 #include "content/public/browser/devtools_agent_host_client.h"
 #include "content/public/browser/navigation_throttle.h"
 
@@ -32,6 +33,8 @@ std::unique_ptr<Target::TargetInfo> CreateInfo(DevToolsAgentHost* host) {
           .Build();
   if (!host->GetOpenerId().empty())
     target_info->SetOpenerId(host->GetOpenerId());
+  if (host->GetBrowserContext())
+    target_info->SetBrowserContextId(host->GetBrowserContext()->UniqueId());
   return target_info;
 }
 

third_party/WebKit/LayoutTests/http/tests/inspector-protocol/target/target-browser-context-expected.txt

+Tests that targets created with window.open share the same browser context.
+Opened a second window
+SUCCESS: All 3 pages belong to the same browser context.
+

third_party/WebKit/LayoutTests/http/tests/inspector-protocol/target/target-browser-context.js

+(async function(testRunner) {
+  const {page, session, dp} = await testRunner.startBlank(
+      `Tests that targets created with window.open share the same browser context.`);
+
+  await dp.Target.setDiscoverTargets({discover: true});
+  session.evaluate(`
+    window.myWindow = window.open('../resources/inspector-protocol-page.html'); undefined;
+  `);
+  testRunner.log('Opened a second window');
+  await dp.Target.onceTargetCreated();
+  const pageTargets = (await dp.Target.getTargets()).result.targetInfos.filter(target => target.type === 'page');
+  const browserContextId = pageTargets[0].browserContextId;
+  if (!browserContextId) {
+    testRunner.log('Found a page target without a browserContextId!');
+    testRunner.log(pageTargets);
+    testRunner.completeTest();
+    return;
+  }
+  for (const pageTarget of pageTargets) {
+    if (pageTarget.browserContextId !== browserContextId) {
+      testRunner.log('Targets have different browserContextIds!');
+      testRunner.log(pageTargets);
+      testRunner.completeTest();
+      return;
+    }
+  }
+  testRunner.log('SUCCESS: All ' + pageTargets.length + ' pages belong to the same browser context.');
+  testRunner.completeTest();
+})

third_party/blink/renderer/core/inspector/browser_protocol.pdl

@@ -5471,6 +5471,7 @@ domain Target
       boolean attached
       # Opener target Id
       optional TargetID openerId
+      experimental optional BrowserContextID browserContextId
 
   experimental type RemoteLocation extends object
     properties